Activates RhoG GTPase by promoting the exchange of GDP by GTP. Required for the formation of membrane ruffles during macropinocytosis. Required for the formation of cup-like structures during trans-endothelial migration of leukocytes. In case of Salmonella enterica infection, activated by SopB, which induces cytoskeleton rearrangements and promotes bacterial entry. Interacts with ICAM1 and RHOG. Isoform 1 is broadly expressed, with highest levels in liver (at protein level). Certain mRNA species appear to be specifically expressed in prostate and liver. Certain mRNA species appear to be up-regulated by androgens in prostate cancer cells. Truncated N-terminus. Intron retention. Truncated N-terminus. Truncated N-terminus.