CD34 and acute myeloid leukemia: Moreover, CD34+ AML stem cells suppress NKG2DL expression via poly-ADP-ribose polymerase 1 (PARP1), implying that NKG2DL mediates immune evasion of NK cell depletion and that genetic or pharmacological inhibition of PARP1 inhibits NKG2DL expression in CD34+ AML stem cells.