Malignant T cells emerging in SNF5fl/f, CD4-Cre+ mice, despite their proliferative capacity in vivo, undergo rapid spontaneous apoptosis when cultured ex vivo (Supplementary Fig. S4A and S4B), suggesting that the provision of extrinsic growth and survival signals by constituents of the TME support lymphoma growth (11). This evidence concerns the gene CD4 and lymphoma.