Mouse liver microsome stability 1.5 µl testing compound or reference compound (500 µM in 5% DMSO and 95% acetonitrile) was mixed with 18.75 µl of 20 mg/mL liver microsome (Corning) and 479.75 µl potassium phosphate buffer (0.1 M potassium phosphate buffer, 1 mM EDTA, pH 7.4). The reaction was started by mixing 30 µL of the above mixture (pre-warmed to 37 °C) with 15 µl of 6 mM NADPH stock solution (pre-warmed to 37 °C). After incubating for 5, 15, 30, or 45 min, 135 µl of acetonitrile containing internal standard was added to stop the reaction. For 0 min, the compound and microsome mixture was mixed with acetonitrile first before adding NADPH. After quench, the reaction mixture was centrifuged, and the supernatant was taken and diluted for LC-MS analysis.