CYP1A1 and liver cancer: Dvořáka et al. (2006) found that CHE did not activate AhR in the rat hepatoma cell line H4IIE at any time or dose test and had no effect on the transcription of AhR. CHE exerted biological effects by inhibiting the catalytic activity of CYP1A1 in the human liver cancer cell line HepG2 but did not affect the expression of CYP1A1 (Zdarilová et al., 2006).