(B) AhR activation by exogenous and endogenous ligands promotes SMAD3 induction. 501Mel cells AhR wild-type or knock-out have been exposed to exogenous and endogenous AhR ligands; TCDD (5nM) or ITE (10µM) or the solvent (DMSO) during 10 days. n=5 biologically independent experiments for AhR WT cells and n=3 for AhR KO cells. Each histogram represents the mean + s.d. (C) AhR activation by exogenous and endogenous AhR ligands promotes TIPARP induction. 501Mel cells have been treated as described in B. n=5 biologically independent experiments for AhR WT cells and n=3 for AhR KO cells. Each histogram represents the mean + s.d.; 