Naproxen glucuronidation by liver microsomes from WT and ΔUgt2 mice. Reactions contained 50–150 µg microsomal protein, 25 µg/ml alamethicin, 100 µM naproxen, and 5 mM UDPGA. (A) Typical chromatogram of reaction products of WT microsomes. (B) Typical chromatogram of reaction products of ΔUgt2 microsomes. (C) Typical chromatogram of a control reaction lacking UDPGA. Microsomes from WT mice formed 46.2 ± 1.9 (mean ± S.E.M., n = 3) nmol NapG/mg of protein, while microsomes from ΔUgt2 mice showed no detectable amount of glucuronide formation.