The ability of Myb to contribute to leukemogenesis is likely through its direct activation of a number of leukemia-promoting genes including Myc [18], CCNB1 [19], Bcl2 [18, 20], Smyd2 [16], and GFI1 [21], as well as its direct repression of key differentiation regulators containing Sfpi1, Runx1, Junb, and Cebpb [22]. This evidence concerns the gene RUNX1 and leukemia.