Western blot analysis

HepG2 and Hep3B cells (5 × 10⁵ cells) were seeded in T25 flasks. One day after seeding, cells were subjected to indicated treatment for 48 hr. Cells were rinsed with ice cold PBS followed by extraction in 500 μl RIPA lysis buffer (Life Technologies, Carlsbad, CA, USA). Equal amounts of proteins, as determined by the BCA protocol (Pierce, Rockford, IL, USA), were run on 10% Tris-Glycine gels (Invitrogen) and then transferred to PVDF membranes (Whatman). The membranes were blocked with 0.1% I-Block (Applied Biosystems, Foster, CA, USA) in PBS-T (0.1% Tween-20), followed by incubation with primary antibodies against P-gp (ab170904, Abcam), MRP2 (R260, Cell Signaling), SF3B3 (ab209402, Abcam), GAPDH (ab9484, Abcam), CD9 (ab92726, Abcam), CD63 (ab134045, Abcam), and Alix (3A9, Cell Signaling). Bands were detected using SuperSignal West Pico chemiluminescent protein detection kits (Pierce). Each experiment was repeated three times. The densities of the bands were analyzed using ImageJ software.