GRLF1 (glucocorticoid receptor DNA binding factor 1) was first identified as a factor that binds to the regulatory region of the human glucocorticoid receptor (GR) gene and represses GR transcription. Later, p190RhoGAP was identified as a protein that associates with p120RasGAP and through sequence comparison, p190RhoGAP and GRLF1 were determined to be one and the same. GRLF1/P190RhoGAP functions as a GTPase activating protein (GAP) for the Rho GTPase and plays an essential role in mediating cytoskeletal reorganization in response to growth factor signals. p190RhoGAP possesses an unusual GTP binding domain that may serve to regulate its GAP activity and the subsequent modulation of RhoGTPase activity. P190RhoGAP forms a significant complex with p120RasGAP. This association has been suggested to represent a method for the coordination of the Ras and Rho signaling pathways.