Driouk et al. demonstrated that valproic acid, an effective histone deacetylase (HDAC) inhibitor, was capable of upregulating NKG2DL expression in acute myeloid leukemia (AML) cells, thus enhancing the anti-tumor efficacy of NKG2D CAR-T cells [48]. Here, HDAC9 is linked to acute myeloid leukemia.