UGT2A1_i2 exhibits no detectable glucuronidation activity against various PAHs. UGT2A1_i2 activity was determined against PAHs that were determined previously to be substrates of UGT2A1_i1. Shown are representative UPLC chromatograms of UGT2A1_i1 activity against 3-OH-B[a]P (A), UGT2A1_i2 activity against 3-OH-B[a]P (B), UGT2A1_i1 activity against 5-methyl-chrysene-1,2-diol (C), and UGT2A1_i2 activity against 5-methyl-chrysene-1,2-diol (D).