Cell viability assay

Cell viability was analyzed by MTS assay (Sigma). Cells (1500–3000) were plated in each well of a 96-well tissue culture plate with 100 μL of medium. The next day, the medium was replaced with 100 μL of fresh medium containing 10 μM Olaparib or 0.5 μM gamma secretase inhibitor, as indicated, and the cells were grown for 7 days. Stock Olaparib and gamma secretase inhibitor were prepared in DMSO. At the end of the treatment period, 10 μL of MTS solution was added to each well, the cells were incubated at 37°C for 1 to 2 h, and absorbance was read at 490 nm. Data are presented as a percentage of the control cells cultivated under the same conditions or the absorbance of the wells.