SAMHD1 and acute myeloid leukemia: Sterile alpha motif (SAM) and histidine-aspartate (HD) domain-containing protein 1 (SAMHD1) have been reported to negatively regulate the level of Ara-CTP, leading to a decrease in its intracellular level, and SAMHD1 is highly upregulated in Ara-C-resistant AML patients, thus decreasing their sensitivity to Ara-C [9, 10].