Cytokine/RAS-induced CD44 upregulation, or de novo transcription of the proteoglycan is not exclusive of B-ALL, but is also characteristic of T-ALL, AML [87, 88], myelodysplastic erythropoiesis, CLL-B [89] and more infrequent leukemia variants, such as erythroleukemia [90] and mast cell leukemia [91]. This evidence concerns the gene CD44 and acute lymphoblastic leukemia.