CYP1B1 and cancer: Interestingly, MCF-7 mammosphere cells showed the highest expression levels of CYP1A1 (27-fold) and CYP1B1 (7-fold) than corresponding adherent cells among all cancer cells (Fig. 1a), followed by T47D (20-fold for CYP1A1 and 4-fold for CYP1B1) (Fig. 1e).