Proteins encoded by ARHGAP4 can regulate the binding between GTPase and rat sarcoma (RAS) family members, whose negative regulation involves the small G protein of the Rho family and associated with tumorigenesis in various cancers, including head and neck squamous cell carcinoma, glioblastoma, breast, lung, pancreatic, liver, colon, and prostate cancers (33, 34). The gene discussed is RAC2; the disease is Familial prostate cancer.