Sleeping Beauty (SB)–induced models of T-cell lymphoma that initiate at distinct developmental time points. (A) An overview of the SB mutagenesis screen to identify driver mutations is shown. (B) Three different Cre-transgenic strains were used to induce SB transposase expression, and thus transposon mutagenesis, at distinct stages of differentiation. (C) A Mantel-Cox log-rank test indicated showed that tumor latency varied significantly between all 3 models (Vav-SB vs Lck-SB [P < .0001], Vav-SB vs CD4-SV [P < .001], Lck-SB vs CD4-SB [P = .026]). Tumors developed rapidly in the Vav-SB model (avg = 11 weeks), but much more slowly in the Lck-SB (avg = 45 weeks) and CD4-SB (avg = 49 weeks) models. DN indicates CD4/CD8 double-negative; ISP, immature single positive; and DP = CD4/CD8 double positive.