This observation agrees with previous studies demonstrating that an AhR-mutated variant of the MCF-7 cell line (AHR10), which exhibits constitutive nuclear localization of AhR and expresses low levels of AhR, exhibits cellular resistance to AF and is refractory to CYP1A1 mRNA induction by the drug [4]. Here, CYP1A1 is linked to atrial fibrillation.