4.4. [3H]-Paclitaxel Accumulation Assay

In brief, cells at a density of 1 × 10⁵ for each well were inoculated onto 24-well plates. The next day, WYE-354 (0.3 µM and 1 µM) or verapamil (1 µM) were added 2 h before co-incubation with [³H]-paclitaxel for another 2 h. After that, the cells were digested and transferred into 5 mL of a scintillation solution. A Packard TRICARB 1900CA liquid scintillation analyzer (Packard Instrument, Downers Grove, IL, USA) was used to measure the radioactivity.