a, b, Western blot analysis showing ARF and p53 levels (a) or Bim levels (b) in MEFs stably infected with control (labelled C), wild-type MYC or mutant MYC vectors. The long (BimL) and extra long (BimEL) isoforms of Bim are shown. c,Western blot analysis of HSCs using antibodies against the indicated proteins. d, Kaplan–Meier curve showing free–free survival following adoptive transfer with Bim−/− HSCs infected with the indicated MYC-expressing retroviruses. e, In vivo GFP imaging showing disseminated lymphomas in mice 34 days after adoptive transfer with Bim−/− HSCs transduced with mutant or wild-type MYC. f,Wild type (Bcl2+/+) and Bcl2−/− MEFs transduced with the indicated retroviruses were incubated in low serum and viability was assessed by trypan blue exclusion. Data represent the mean ± standard deviation of three independent experiments.