Has GTPase activator activity toward RHOA; RHOA activation results in GTP hydrolysis and conversion from an active GTP-bound to an inactive GDP-bound state (PubMed:24259668, PubMed:41086021). Lacks GTPase activator activity toward RAC1 or CDC42 (PubMed:24259668). . This is the function of ARHGAP19 (Rho GTPase activating protein 19, Ensembl gene identifier ENSG00000213390).