ARHGAP20 encodes a Rho GTPase-activating protein that inactivates Rho-family GTPases by promoting their conversion to an inactive GDP-bound state 1. The protein functions as a negative regulator of small GTPase-mediated signal transduction and contains a conserved RhoGAP domain along with RA domain and Annexin-like repeats 2. ARHGAP20 is implicated in B-cell chr11 lymphocytic leukemia (B-CLL) pathogenesis. The gene is located within the minimally deleted region 11q22-23, which is frequently deleted in B-CLL and associated with poor survival 1. Gene disruption and altered regulation of ARHGAP20—rather than point mutations—appear to drive leukemogenesis; notably, ARHGAP20 shows counterintuitive upregulation in CLL cases with 11q22-23 deletions compared to cases without genetic lesions 3. This paradoxical expression pattern, also observed in cases with 13q14 deletions, suggests an intriguing compensatory regulatory mechanism 3. Beyond hematologic malignancies, ARHGAP20 has emerging relevance in other cancers. The gene was identified as a tumor microenvironment-related prognostic marker in rectal cancer, with protein-level differences between tumor and normal tissues 4. Additionally, ARHGAP20 phosphorylation shows sex-biased regulation in murine models 5, and the broader ARHGAP family represents cancer-associated genes where dysregulation promotes tumorigenesis through disrupted Rho/Rac/Cdc42 GTPase signaling 6.