ABT-888 is inactive to SIRT2 (>5 μM). [1] ABT-888 inhibits the PARP activity with EC50 of 2 nM in C41 cells. [2] ABT-888 could decrease the PAR levels in both irradiated and nonirradiated H460 cells. ABT-888 also reduces clonogenic survival and inhibits DNA repair by PARP-1 inhibition in H460 cells. ABT-888 increases apoptosis and autophagy in H460 cells when combination with radiation. [3] ABT-888 also inhibits PARP activity in H1299, DU145 and 22RV1 cells and the inhibition is independent of p53 function. ABT-888 (10 μM) suppresses the surviving fraction (SF) by 43% in the clonogenic H1299 cells. ABT-888 shows effective radiosensitivity in oxic H1299 cells. Furthermore, ABT-888 could attenuate the SF of hypoxic-irradiated cells including H1299, DU145 and 22RV1. [4]