Ras GTPase-activating protein 4 is an enzyme that in humans is encoded by the RASA4 gene.
This gene encodes a member of the GAP1 family of GTPase-activating proteins that suppresses the Ras/mitogen-activated protein kinase pathway in response to Ca(2+). Stimuli that increase intracellular Ca(2+) levels result in the translocation of this protein to the plasma membrane, where it activates as GTPase activity. Consequently, Ras is converted from the active GTP-bound state to the inactive GDP-bound state and no longer activates downstream pathways that regulate gene expression, cell growth, and differentiation. Multiple transcript variants encoding different isoforms have been found for this gene.
