CYP1A1 and neoplasm: In a paper about a possible mechanism controlling the expression of AhR-regulated CYP1 enzymes in colon carcinoma HCT-116 cells, it was shown that aberrant proliferative Wnt/β-catenin signaling in tumor cells can attenuate CYP1 induction through competition (with coregulatory protein p300) for the binding to promoters of CYP1 genes and via the displacement of p300 from the regulatory regions of a CYP1 gene [186].