MGMT and acute myeloid leukemia: The protective effect of MGMT against TMZ is particularly detrimental in AML, because the majority of AML patients present with significant MGMT expression in their tumor tissue [26], consistent with laboratory studies that only 25% of leukemia cells harbor low levels of MGMT [27], and inhibition of MGMT in vitro greatly sensitizes leukemia cells to TMZ [28].