We previously demonstrated that panobinostat (a pan-HDACI) suppressed the expression of BRCA1, CHK1, and RAD51 which play critical roles in the DNA damage response (DDR), leading to induction of DNA DSBs and apoptosis, and abrogation of the activation of the cell cycle checkpoints induced by ara-C or DNR in AML cells [14]. Here, CHEK1 is linked to acute myeloid leukemia.