RPS6KB1 and nonpapillary renal cell carcinoma: Overexpression of the RNF26 T348A mutant had less of an effect on the protein levels of TSC1 and p-S6K1 (T389) than overexpression of wild-type RNF26 with or without overexpression of CDK4 in ccRCC cells (Fig. 6n, o).