Nicotine fails to interfere with paclitaxel-induced apoptosis (A) and sub-G1 DNA content (B) of NSCLC cells. A549 and H460 cells were treated with nicotine (1 μM), staurosporine (2 μM), paclitaxel (100 nM), or the combination of paclitaxel and nicotine for 48 hours. Quantification of apoptotic cells and sub-G1 DNA content was determined by the Annexin V/PI assay and PI staining, respectively, followed by flow cytometry analysis. ***P < 0.001, ****P < 0.0001 versus control. n.s., not significant. Data are expressed as the mean ± S.E.M. of three (A) or two (B) independent experiments.