Several leukemia-related specific pathways [43–45], including co-stimulation by the CD28 family, HSC and multipotent progenitors, targets of MLL-AF9 fusion pathway, AML prognosis, TCR pathway, P38 and MK2 pathway, and FLT3 signaling, which were demonstrated to play crucial roles in the regulation of leukemogenesis and progression. This evidence concerns the gene FLT3 and leukemia.