Basal level of NQO1 mRNA, protein expression, and enzyme activity of CCA cells and NQO1 protein induction by chemotherapeutic agents (5-FU, Doxo, and Gem). (A) Basal NQO1 mRNA expression in CCA cell lines (KKU-100 and KKU-M214) and two other cell lines (Chang and MMNK1 cells) analyzed by qPCR. The bars represent relative mRNA expression of NQO1 normalized with β-actin as internal control. *p < 0.05 vs KKU-100 cells. (B) Basal NQO1 enzyme activity analyzed by enzymatic methods. *p < 0.05 vs KKU-100 cells. (C) Basal NQO1 protein expression analyzed by Western Blot analysis using β-actin as internal control. Representative images of NQO1 and β-actin are shown in the top panel of the figure. *p < 0.05 vs KKU-100 cells. (D) Effect of chemotherapeutic agents on NQO1 protein expression in KKU-100 cells. Cells were exposed to 5-FU (3 μM), Doxo (0.1 μM), and Gem (0.1 μM) for 24 hr. Data represent mean ± SEM, each from three separated experiments. *p < 0.05 vs the untreated control.