AHR and cancer: Previous work has suggested that p27Kip1 can be induced by TCDD-mediated AhR activation, resulting in cell cycle arrest (Kolluri et al., 1999), while other studies demonstrated that TCDD treatment of human or mouse cancer cell lines resulted in the recruitment of AhR to E2F-dependent promoters with subsequent repression through a mechanism involving displacement of p300 (Marlowe et al., 2004).