Ratios of mono-oxidation metabolites 1 and 2 (M1 and M2) to atazanavir (ATV) concentration in 75 CYP3A5 expressers (n = 49) and non-expressers (n = 26). (a) Log10 M1/atazanavir ratios in expressers versus non-expressers. (b) Log10 M2/atazanavir ratios in expressers versus non-expressers.