RACGAP1 (Rac GTPase-activating protein 1) is a multifunctional regulatory protein with critical roles in cell division and disease pathogenesis. Primary Function: RACGAP1 serves as a component of the centralspindlin complex essential for cytokinesis, regulating myosin contractile ring formation and controlling sequential binding to ECT2 and RAB11FIP3 during cleavage furrow ingression and abscission 1. It demonstrates GTPase-activating activity toward CDC42 and RAC1, with lesser activity toward RHOA [UniProt annotation]. Beyond its canonical GAP function, RACGAP1 plays non-canonical roles in hematopoietic cell growth and differentiation 2 and is critical for erythropoiesis 3. Disease Relevance: RACGAP1 mutations cause congenital dyserythropoietic anemia 3B (autosomal recessive) [NCBI annotation]. In cancer biology, RACGAP1 is highly expressed across multiple tumor types and correlates with poor prognosis 4. Its oncogenic mechanisms include promoting RhoA/RAC1 activation to facilitate nuclear translocation of signaling molecules and cytoskeletal remodeling 5, suppressing ferroptosis through CPT1A-dependent fatty acid metabolism in triple-negative breast cancer 6, and inhibiting anti-tumor immunity 7. Clinical Significance: RACGAP1 represents a potential prognostic biomarker and therapeutic target across multiple cancers 4, with emerging evidence supporting its targeting in bladder cancer and other malignancies.