Mouse Hepatocyte stability 50 µl of pre-warmed hepatocytes (2 × 10 6 cells/ml) in suspension media (Krebs-Henseleit buffer (Sigma) containing 5.6 g/l HEPES) was mixed with 50 µl prewarmed compound dosing solution (2 µM in Krebs-Henseleit buffer with 1% DMSO). After incubating at 37 °C for 15, 30, 60 or 120 min, 100 µl of acetonitrile containing internal standard was added to quench the reaction. For 0 min incubation, acetonitrile was mixed with hepatocytes first before adding compound solution. After quenching, the mixture was shaken at the vibrator for 10 min (600 rpm/min) and then sonicated for 2 min before centrifugation (5594 g for 15 min). The supernatant was taken and diluted for LC-MS analysis.