Human breast cancer cell lines (MCF-7 and ZR-75-1) were
purchased from American Type Culture Collection (ATCC). Both
cells were maintained in RPMI-1640 culture medium supplemented
with 10% fetal bovine serum, 1% penicillin/streptomycin
and 1% L-glutamine. The cells were cultured and maintained at
37 °C in a 5% CO2 humidified incubator.