CYP3A4 activity

To measure the CYP3A4 activity, we performed lytic assays by using a P450-Glo CYP3A4 assay kit (V9001; Promega, WI, USA). Luciferin-IPA was used for the CYP3A4 substrate. We measured the fluorescence activity with a luminometer (Lumat LB 9507; Berthold Technologies, Baden-Wurttemberg, Germany) according to the manufacturer’s instructions. The CYP3A4 activities were normalized with the protein content per well by using a Pierce bicinchoninic acid (BCA) protein assay kit (23227; Thermo Fisher Scientific) according to the manufacturer’s instructions. As an inhibitor of CYP3A4, 10 μM ketoconazole (116-00551; Fujifilm Wako Pure Chemical Industries) was incubated with the substrate.