ARHGAP1 and neoplasm: Furthermore, p190Rho-GAP has been shown to be activated and reduce RhoA-activity in a Rac1-dependent manner in tumor cells and fibroblasts [59, 116] and RA-Rho-GAP and ARAP3 are activated by binding of Rap1, probably inducing the downregulation of RhoA in smooth muscle cells [184] (Table 1).