Induction of TiParp. YAMC cells were treated with TCDD (alone), indole-3-aldehyde (A), indole (B), indole-3-acetate (C), or tryptamine (D) alone and in combination with TCDD for 24 hours, and TiParp was determined by real-time PCR. Results are expressed as mean ± S.E. (three replicates), and significant (P < 0.05) induction (*) or inhibition (**) of TCDD-induced TiParp is indicated.