Many papers demonstrate that cN-II activity is involved in resistance to a number of nucleoside analogs utilized as drugs in the therapy of several kind of tumors, mainly hematological malignancies such as acute myeloid leukemia (AML), chronic lymphoid leukemia (CLL) or acute lymphoblastic leukemia (ALL), but also of some solid tumors, such as non-small cell lung cancer [40,41]. This evidence concerns the gene NT5C2 and acute myeloid leukemia.