Mepicm medium

The human mammary epithelial cells (MCF-10A) and BC cell lines (MCF-7 and SK-BR-3) were provided by ATCC (American Type Culture Collection, Manassas, VA, USA). MCF-10A cells were cultured in MEpiCM Medium (ScienCell) supplemented with 10% FBS (Gibco), 1% MEpiCGS (ScienCell), and 1% penicillin/streptomycin (PS, ScienCell) at 37°C in 5% CO₂. MCF-7 cells were cultured in DMEM (Gibco) supplemented with 10% FBS (Gibco), 0.01 mg/mL human recombinant insulin (HRI, Solarbio), and 1% PS (HyClone) at 37°C in 5% CO₂. SK-BR-3 cells were cultured in RPMI 1640 (Gibco) supplemented with 10% FBS (Gibco) and 1% PS (HyClone) at 37°C (no CO₂).

Post-stasis variant human mammary epithelial cells (vHMECs) were obtained from Cell Applications Inc. (San Diego, CA, USA). vHMECs were cultured with serum-free MEpiCM medium supplemented with MEpiCGS and penicillin/streptomycin (all from ScienCell Research Laboratories, Carlsbad, CA, USA), or with M87AX [89 (link)]. Growth conditions were 5% CO₂ and 37 °C. Culture population doublings (PDs) were calculated using the formula: PD = PD_initial + log₂ (N_final/N_initial), where N_initial is the number of viable cells plated, and N_final is the number of viable cells harvested.