ERBB2 and breast cancer: It is noteworthy to mention that although, we showed that PARP1 inhibition confers a protection from APO866-induced cell toxicity in a broad range of leukemia cells, it was reported elsewhere that NAMPT inhibition significantly enhanced the sensitivity of triple-negative (ER-, PR-, HER2-negative) breast cancer cells to olaparib (PARP1 inhibitor) treatment [51].