Menin stimulates homology-directed repair through Chk1 and the region required is 1-228: a 2010 paper that is cited in no entry of this graph and in no reference list of the 2026 paper that reports the same conclusion

No three-dimensional model is available for this protein, so the map above is the whole picture. That is itself informative: AlphaFold does not model chains this long, and the parts that have been crystallised are held under the entries for the individual domains.

• If menin stimulates homologous recombination, a menin inhibitor given to a child is a partial, reversible HR inhibitor, and HR inhibition is the mechanism by which several agents cause secondary malignancy. That risk is invisible in a response-rate endpoint and in a two-year follow-up.
• The converse is a missed opportunity rather than a harm: if menin loss impairs HR, menin inhibitors plus a PARP inhibitor or a crosslinker is a synthetic-lethal combination nobody has tested in KMT2A-rearranged disease, and the graph already holds `ana-the-menin-parp-experiment-survives-and-gains-a-rival-rationale`.
• Building either argument on a 228-residue deletion is the weak point. If that construct is simply unfolded, the HR rationale loses one of its three legs and the remaining two are a paywalled 2003 co-immunoprecipitation and one 2026 paper in a lung line.

1. Is the menin 1-228 deletion construct folded? A thermal shift on it against full-length menin would separate 'lost interface' from 'lost protein' in an afternoon, and until somebody runs it the 1-228 region claim cannot be used.
2. Does menin bind Chk1 directly, and if so where? The 2010 abstract reports an in vivo interaction and a truncation; there is no structure, no affinity and no reciprocal mapping on Chk1.
3. Do the 2010 I-SceI result and the 2026 DR-GFP-class result agree quantitatively? Both measure homology-directed repair with an endonuclease-induced break, sixteen years apart, in different cells, and nobody has put the two numbers side by side.
4. Does the 2010 result survive in a KMT2A-rearranged cell? Every menin DNA-repair experiment in the literature is in a fibroblast, a lung line or a generic human line, and the disease this graph is about is not represented in any of them.

1. E1moderate confidence 3 of 5: One strong study, or several smaller consistent ones.paper

   In human cells, menin stimulates homology-directed DNA repair induced by the rare endonuclease I-SceI and accumulates with Chk1 at the site of the double-strand break; menin and Chk1 interact in vivo; and deletion of the first 228 amino acids of menin impairs both the Chk1 interaction and the ability to stimulate HD repair.

   Menin stimulates homology-directed DNA repair. · Gallo A, Agnese S, Esposito I, Galgani M, Avvedimento VE · FEBS Letters 2010
   PMID 20969866DOI
   ▸What this evidence cannot show

   ABSTRACT ONLY - the full text was not retrieved in this beat and no route beyond PubMed was attempted, so n, cell line, the localisation method and the deletion construct's expression and stability are all unknown. `moderate` rather than `strong` for that reason and for one substantive one: deleting menin's N-terminal 228 residues removes the whole NTD and the whole thumb, 37% of the protein and 21 of the 29 residues that contact the KMT2A MBM1 peptide, so the construct may be reporting misfolding rather than a lost interface. The paper is not a leukaemia paper, contains no KMT2A fusion and is not in a haematopoietic cell. The authors' own wording for the model is 'suggesting'.

   ▸Evidence that argues against this (1)

   • A Drosophila study designed to test whether MEN1 acts with the Fanconi pathway in crosslink repair found different mutation spectra and no genetic interaction, so menin's contribution to repair is not a single coherent pathway claim and the 2010 result should not be read as confirming the 2003 one. Marek LR et al. 2008
2. E2strong confidence 4 of 5: Replicated in peer-reviewed work by more than one group.paper

   The 2026 paper asserting that menin is a key scaffold mediator for homologous recombination repair does not cite the 2010 paper titled 'Menin stimulates homology-directed DNA repair'; it reaches the Chk1 connection through a 2006 paper on menin localisation to chromatin via an ATR-CHK1 pathway, in one introductory sentence grouping RPA, FANCD2 and Chk1.

   The tumor suppressor menin is a key scaffold mediator for homologous recombination repair. · Lian A, Zhu X, Jin B, Gu G, Xu B, Zhang L, et al. · Nucleic Acids Research 2026
   PMID 42578372DOI
   ▸What this evidence cannot show

   Bounded to the reference list as served by Europe PMC in the PMC13458390 full text (96,530 characters), searched for the author surname, for 'febslet' and for 'homology-directed'; the only 'homology-directed' hit in the reference list is Pierce et al. 1999 on XRCC3. A reference list can be incomplete in a converted full text, and an uncited paper is not a hidden paper - the 2010 work is indexed in PubMed and the omission may be an ordinary oversight rather than anything more. This entry records the omission, not a motive.

   ▸Evidence that argues against this (1)

   • The 2026 paper's claim is narrower than its title and is about a specific scaffolding mechanism - sequential recruitment of SETD2, LEDGF and CtIP with H3K36me3 reprogramming - which the 2010 paper does not address. On that mechanism there is no priority question at all, and reading the omission as a priority dispute would overstate it. Gallo A et al. 2010
3. E3established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.database

   Menin 1-228 comprises 88 residues of the NTD/palm spatial lobe, 134 of the thumb and 5 of the fingers; it overlaps UniProt's FANCD2 region 214-390 by 15 residues and the gamma-H2A.X motif 371-400 by none; and it contains only 7 of the 21-26 menin residues contacted by any of the four clinical menin inhibitors, all seven in the 155-182 stretch.

   analyses/q36-menin-residue-axis/run.py - lobe assignment and ligand footprints on PDB 3U84, 7UJ4, 8VA6, 9WKU, 8IG0 and 4GQ6, run 2026-09-22 · RCSB PDB, computed 2026
   ▸What this evidence cannot show

   Lobe assignment is a contact-graph clustering of one crystal form with the stated boundary uncertainties in `ana-q36-menin-residue-axis`; the NTD|thumb boundary in particular is a convention that cuts a helix. Residue 1 is unmodelled in the reference deposit. The overlap arithmetic is exact and needs no structure; only the lobe composition depends on the parse.

   ▸Evidence that argues against this (1)

   • Three regions failing to overlap is equally consistent with menin having three separate repair-relevant surfaces as with two of the three maps being artefacts of large deletions. This entry argues the latter from the widths, which is an argument from study design and not a measurement of either surface. Huang J et al. 2012
4. E4established confidence 5 of 5: Multiple independent lines of evidence; treated as settled in the field.database

   PubMed returns 0 records for menin[tiab] AND H2AX[tiab] and 1 for menin[tiab] AND "H2A.X"[tiab], with non-empty query translations in both cases and both operands large (menin 1,264; H2AX 6,971; "H2A.X" 784), so the unpunctuated spelling produces a genuine-looking zero on the only paper that maps the menin-gamma-H2A.X contact; menin[tiab] AND "homologous recombination"[tiab] returns 3 and menin[tiab] AND "DNA repair"[tiab] returns 19.

   PubMed E-utilities esearch via scripts/pubmed_safe.py, query translations read back, 2026-09-22 · NCBI PubMed 2026
   ▸What this evidence cannot show

   Counts move as PubMed indexes. All three records from the homologous-recombination query were opened and their titles read, per the registry row warning that a non-zero hit count is not evidence the token is in any document you can read. The name list searched for the compound arm of the related bounded absence was bleximenib, JNJ-75276617 and JNJ75276617; for the readout arm, H2AX, "H2A.X", "gamma-H2A.X", "DNA repair", "DNA damage" and "homologous recombination". This is a title/abstract bound only - a gamma-H2A.X western in a supplementary figure of a bleximenib paper would be invisible to it (brief rule 80).

   ▸Evidence that argues against this (1)

   • The spelling asymmetry may be partly an artefact of which journals use which style rather than a general trap, and 6,971 against 784 suggests the unpunctuated form is the majority usage - so for most questions H2AX is the better token and it is only this one paper that is reachable solely through the punctuated form. Lian A et al. 2026

• related to →MEN1 / menin — the adaptor the fusion cannot work without

  menin stimulates homology-directed repair; the region claimed is 1-228

• binds →CHEK1 (CHK1) - the node where this graph's chidamide synergy actually lands, and the reason that synergy is an HR-impairment argument

  menin and Chk1 interact in vivo and co-accumulate at the I-SceI break; abstract-level evidence only

• related to →The menin-gamma-H2A.X motif, menin Val371-Gln400: necessary, sufficient as a peptide, and the nine residues at its centre have never been seen in any of the 69 menin structures

  a third DNA-repair region claim, 1-228, with zero overlap with the gamma-H2A.X motif

• related to →Menin-FANCD2: one 2003 co-immunoprecipitation, a curated sufficient region of menin 214-390, and nothing since

  overlaps the curated FANCD2 region by 15 of 228 residues

• depends on →A residue axis for menin, derived from coordinates: three spatial lobes, not four named ones, and the sharpest seam in the protein runs through the drug pocket

  lobe composition of the 1-228 region comes from that parse

• supports →UniProt's menin 214-390 FANCD2 region is not a surface: it spans three spatial lobes and 29.9% of menin's solvent-accessible area, so its twenty-residue overlap with the gamma-H2A.X motif is what chance gives you

  a third truncation bracket, and the union of the three covers 66% of menin

• related to →Does a menin inhibitor break homologous recombination? Test the menin - SETD2 - LEDGF - CtIP chain in a blast, before the next genotoxic combination is designed

  supplies a sixteen-year-older rationale for that experiment than the one it cites