Kinetics of 4-phenylphenol (A), 4-methylumbelliferone (B), and 4-nitrophenol (D) glucuronidation by UGT2A2. The aglycone substrate in the kinetic analysis for UDPGA (C) was 750 μM 4-phenylphenol. The analyses were done in triplicates and the SD error bars are presented (even if they are not easily visible in panels A, B, and D, due to very small differences between the triplicate determinations).