Paradoxically, METTL1 demonstrates context-dependent tumor-suppressive activity, particularly in cancers with specific molecular vulnerabilities—such as BRCA1-deficient breast cancer (BRCA) or IDH-mutant gliomas—where it restricts tumor progression through mechanisms involving tRNA modification-mediated cell cycle arrest (G2/M phase prolongation) and enhanced genome stability maintenance (49). The gene discussed is BRCA1; the disease is neoplasm.