(A) PRMDR (final monomeric protein concentrations of 0.25, 0.375, 0.5, 0.75, 1.0 and 2.0 μM) was incubated for 16 h at 37 °C in 150 mM ammonium acetate buffer containing 100 μg · ml−1 BSA without JE-2147 or (B) with 1 μM JE-2147 (+JE). The column effluent was monitored for PRMDR-specific ions (m/z 1086, 10+) and (m/z 987.6, 11+) in SIM mode. The m/z 1086 is shown. The earlier- and later-eluting PRMDR peaks had approximate elution times of 10.8 and 11.3 min respectively. This experiment was repeated three times with similar results and a representative experiment is shown.