Coexpression of MYC and BCL-XL or BCL-2 strongly favored tumor development towards myeloid leukemia, whereas coexpression of MYC and FLIPL did not affect the distribution of myeloid versus lymphoid tumor cells, but changed the ratio between single CD4+ and double positive CD4+CD8+ T-cell lymphomas. The gene discussed is BCL2; the disease is myeloid leukemia.