Effect of SXR overexpression on LS180 and HCT116 survival after SN-38 treatment. A. Detection of carboxylesterase 2 (CE2) by western blot in LS180, HepG2 and HCT116 cells. B. and C. LS180 cells (B) and HCT116 cells (C) were transfected with control or SXR vector for 24 h, then treated for 72 h with different CPT-11 concentrations. The SXR overexpression was confirmed by western blot after 24 h transfection. Cell viability following irinotecan exposure was determined by SRB assay by comparison with untreated cells. Each point represents the mean of 3 replicates and the experiment has been repeated 3 times. All results are expressed as the mean ± SE and obtained data were analysed for statistical differences by Student's t test. A p value of less than 0.05 was considered statistically significant (star indicates p < 0.05).