We have been studying the DLC1 tumor suppressor gene, which encodes a cytoplasmic Rho-GAP (GTPase-activating protein) that catalyzes the hydrolysis of active Rho-GTP to inactive Rho-GDP5,6, and have identified several oncoprotein kinases—namely AKT, SRC (and SRC family kinases), and ERK—that directly phosphorylate and attenuate the Rho-GAP and tumor suppressor activities of the DLC17,8. The gene discussed is ARHGAP1; the disease is neoplasm.