Interaction of isoflavones with SCFAs. Caco2 and YAMC cells were treated with 10 nM TCDD, biochanin, and genistein alone or in combination with SCFAs (acetate, propionate, and butyrate), and induction of CYP1A1 (A), CYP1B1 (B), and UGT1A1 (C) mRNA levels was determined by real time PCR as outlined in the Experimental Procedures. Results are expressed as means ± SD for at least 3 determinations per treatment group; significant (p < 0.05) induction is indicated (*), and SCFA-enhanced induction is indicated (**).