RBL1 and hepatocellular carcinoma: The idea that inactivation of several RB family members may be required to observe a strong phenotype during HCC development is supported by the observation that most of the events known to inactivate the RB pathway are upstream events and may inactivate RB, p107, and p130 simultaneously [65], [66], [67], [68], [69], [70], [71], [72], [73].