DMU2105 (Compound 7k) shows 74 and 120-fold selectivity for CYP1B1 over CYP1A1 and CYP1A2. In the presence of DMU2105 however, the EC50 goes down to 1 μM indicating that the cells have suffered from toxicity which may have been mediated by CYP1B1 inhibition. Un-transfected cells (HEK293: pcDNA3.1), when treated with cisplatin and DMU2105 (10×IC50) do not show any perceptible decrease of cisplatin EC50 (8.5 μM ± 0.9).