Figure 1.

AHR-dependent signaling pathways. Inactive AHR is part of a cytosolic multiprotein. complex consisting of a HSP90 dimer, other chaperone molecules and tyrosine kinase c-Src. Upon ligand binding, the multiprotein complex dissociates and AHR translocates into the nucleus. Nuclear AHR heterodimerizes with ARNT and binds to the enhancer region of target genes, for instance encoding CYP1A1, CYP1B1, and AHRR, to enhance their expression. In addition to this canonical pathway, the AHR ligand-driven release of c-Src from the cytosolic multiportion complex may stimulate EGFR and downstream mitogen-activated protein kinases, resulting in the transcriptional induction of another set of genes.