RB1 and nonpapillary renal cell carcinoma: To determine the effect of pRb hyperstabilization on the viability of ccRCC cells, we depleted pRb from several VHL-deficient ccRCC cell lines using pRb-targeting siRNAs (Supplementary Fig. S5) and analyzed cell viability using a sulforhodamine B (SRB) colorimetric assay.