RPS6KB1 and liver cancer: Strikingly, UBE2F knockdown significantly inactivated mTORC1 activity, as reflected by remarkable reduction in the levels of p4E-BP1 and pS6K1, as well as the ratio of p4E-BP1/4E-BP1 and pS6K1/S6K1 in two lines of liver cancer cells (Figs. 2A and EV2A–D).