Similarly, infection of cultured renal cells from wild type mice with a lentiviral vector expressing both shRNA-Tsc2 and shRNA-Cdkn2a (shRNA-Tsc2 + Cdkn2a) (Supplementary Fig. 2c) increased proliferation rate compared with shRNA-Cdkn2a knockdown and allowed growth in soft agar (Fig. 1b and Supplementary Fig. 2e). This evidence concerns the gene CDKN2A and infection.