AHR and breast cancer: In our study in the MDA-MB231 breast cancer cell line, the AhR depletion resulted in substantial down-regulation of KYNU, the enzyme which catalyzes the conversion of kyn to anthranilic acid and the conversion of 3-hydroxykynurenine (3HK) to 3-hydroxyanthranilic acid; taking into account that the mammalian KYNU preferentially targets the 3HK over kyn [19].