Fig. 7. 5-HT potentiates CYP1A1 induction by β-NF and ICZ. Caco-2 cells were plated at low density and allowed to differentiate for 10-14 d in medium containing 10% serum before treatments were performed. Cells were treated with 1 μM β-NF (A) or 50 nM ICZ (B) in the presence of 5-HT (10 μM) for 16 h in TRP-free and serum-free medium. Data represent the relative expression of CYP1A1 mRNA quantified by qPCR as compared to untreated cells (n = 4). Data analyzed by 1-way ANOVA followed by Tukey's multiple comparisons test. *P<0.05, ****P<0.0001 compared to untreated cells or between groups as indicated.