KYSE-30 cells were challenged with P. gingivalis in the presence or absence of paclitaxel for the times indicated, and then whole-cell lysates were collected and analysed by Western blots using antibodies against STAT3, caspase-3, or GAPDH (a, b); cells pre-treated with a STAT3 inhibitor (WP1066, 20 µM) were challenged with P. gingivalis in the presence or absence of paclitaxel, then the staining of annexin V/PI and expression of caspase-3 were used to determine apoptotic or necrotic cell death by flow cytometry and Western blots and, respectively (c, d); inhibition of STAT3 enhances the expression of caspase-3 (d) and cell apoptosis (c) upon challenge with P. gingivalis. e Whole-cell lysates of KYSE-30 cells treated with P. gingivalis at the indicated time points were probed for levels of cyclin D3, E1, and total- and phospho-CDK2; f normalised ratios of different regulatory proteins to GAPDH were determined by densitometry; all results are the average of at least three independent experiments. Error bars represent standard deviation. * and *** represent P < 0.05 and P < 0.001, respectively.