The HepG2, and A549 cells were cultured in
RPMI 1640 medium (Hyclone, Logan, UT, USA). Both
cell lines were supplemented with 10% heat inactivated
fetal bovine serum (Hyclone), 100 U/mL penicillin and
100 μg/mL streptomycin (Gibco BRL, Grand Island, NY).
All cell lines were maintained at 37℃ in a 5% CO2 incubator
and the media were changed twice weekly.