This gene encodes a protein which contains an N-terminal sterile alpha motif (SAM) for protein-protein interactions, followed by an ATP/GTP-binding motif, a GTPase-activating protein (GAP) domain, and a C-terminal STAR-related lipid transfer (START) domain. It may be involved in regulation of cytoskeletal reorganization, cell proliferation, and cell motility, and acts as a tumor suppressor in hepatoma cells. The gene is located in a region of chromosome 13 that is associated with loss of heterozygosity in hepatocellular carcinomas. Alternatively spliced transcript variants encoding different isoforms have been described for this gene. [provided by RefSeq, Aug 2011],function:GTPase-activating protein for RhoA, and perhaps for Cdc42. May be involved in regulation of cytoskeletal reorganization, cell proliferation and cell motility. Acts a tumor suppressor in hepatocellular carcinoma cells.,similarity:Contains 1 Rho-GAP domain.,similarity:Contains 1 SAM (sterile alpha motif) domain.,similarity:Contains 1 START domain.,subunit:Homodimer. Interacts with TAX1BP1.,tissue specificity:Ubiquitously expressed. Underexpressed in hepatocellular carcinoma cells and some breast cancer cell lines.,