AHR and breast cancer: Gene and protein expression analyses of B[a]P- and PCB126-treated AHR-knockdown (HaCaT-shAHR) and CRISPR/Cas12-engineered AHR-knockout (HaCaT-AHR-KO) keratinocytes, AHR-knockout human MCF-7 breast cancer cells (MCF-7-AHR-KO) and respective AHR-proficient controls confirmed a ligand-specific and AHR-dependent upregulation of AKR1C3 (Fig. 1c,d, S2c,d).