['To investigate the relationship between the expression of glucose-regulated protein (GRP78) and resistance to VP-16 in the NCI-H460 cell line.', 'RT-PCR, real-time RT-PCR and Western blotting were used in analyzing the expression of GRP78 at mRNA and protein levels in the NCI-H460 cell line induced by A23187 at different concentrations. Cell survival with VP-16 was determined using a colony-formation assay with the account of IC50.', 'The expression of GRP78 at both the mRNA and protein levels was higher in the NCI-H460 cell line induced by A23187. A23187 treatment resulted in up to 4.8-fold elevation of GRP78 mRNA and up to 3.2-fold elevation of GRP78 protein in the experimental cells compared to the controls, all in a dose-dependent manner. The IC50s for VP-16 in the cells pretreated with different concentrations of A23187 (0, 1, 2, 4 and 6 microM) were: 12.11 +/- 0.83, 12.68 +/- 1.04, 25.82 +/- 1.83, 37.46 +/- 1.89 and 45.19 +/- 2.34 microM, respectively. Compared to the control, there was a significant elevation of IC50 for VP-16 in the cells pretreated with A23187. Survival curve analysis also showed that the induction of A23187 caused a significantly longer survival for the cells subjected to VP-16 treatment (p < 0.05).'] Is vP-16 resistance in the NCI-H460 human lung cancer cell line significantly associated with glucose-regulated protein78 ( GRP78 ) induction?