(Gibco BRL) supplemented with 10% neonatal bovine serum (NBS) (Sijiqing
Biotech, Hangzhou, China). 4T1, H1975, and KB cells were incubated
in RPMI-1640 (Gibco BRL) containing 10% fetal bovine serum (Gibco
BRL). RG, HK-2, and MCF-7 cells were grown in DMEM (Gibco BRL) containing
10% fetal bovine serum (Gibco BRL). All cell lines were maintained
in a 5% CO2-humidified atmosphere at 37 °C.