RSU1 and hepatocellular carcinoma: This model may provide an explanation for the initial observation, based upon which the name Ras Suppressor 1 (RSU1) was coined, that overexpression of RSU1 suppresses v-Ki-Ras–induced oncogenic transformation (29) as well as clinical observations that loss or reduced expression or mutations of RSU1 was associated with certain types of human cancers (e.g., hepatocellular carcinoma and gliomas) (37, 38, 39).