(A) 10−11M taurodeoxycholic acid (TDCA, 24h) significantly increased 3H-thymidine incorporation. (B) Western blot analysis, (C) summarized data and (D) H2O2 measurement showed that 10−11 M TDCA significantly increased NOX5-S expression and H2O2 production. (E) Knockdown of NOX5-S by NOX5 small interfering RNA blocked TDCA-induced increase in thymidine incorporation. The data suggest that TDCA may increase NOX5-S expression, H2O2 production and cell proliferation in FLO cells and that TDCA-induced increase in cell proliferation may depend on activation of NOX5-S. N=3, ANOVA, * P<0.05, ** P<0.01, compared with control.