(A) SCC38 cells were treated with PNUTS siRNA (#1) and PARPi (olaparib, 10 μM), as indicated. One day after the treatment, cells were harvested and analyzed by immunoblotting for active caspase-3, PNUTS, and α-tubulin. (B) SCC38 cells were treated with as in panel A, and measured by the trypan blue exclusion assay for cell death. The mean value and standard deviation were calculated from 3 independent experiments. Statistical significance was analyzed using an unpaired 2-tailed Student’s t-test. A p-value<0.05 was considered statistically significant (*), and p<0.001 was highly significant (***). (C) SCC38 cells were treated with PNUTS siRNA and olaparib as in panel A. The relative cell viability is shown. (D) The colonogenic assay was performed as described in Materials and Methods. The numbers of colonies were normalized to the untreated control. The mean value and standard deviation were calculated from 3 independent experiments. Statistical significance was analyzed using an unpaired 2-tailed Student’s t-test.