4.1. Cell Culture

The human NB cell line SK-N-BE(2)-C (ATCC, CRL-2268) was cultured at 37 °C and 5% CO₂ in minimum essential medium (MEM, HyClone, Thermo Fisher Scientific, MA, USA) supplemented with 10% fetal bovine serum (FBS) (Sigma-Aldrich Sweden AB, Stockholm, Sweden) and 1% penicillin/streptomycin (GIBCO, MA, USA). To generate vincristine-resistant cells (Be2c-VCR), SK-N-BE(2)-C cells were cultured for 7 months with gradually increased concentrations of vincristine ranging from 1 to 10 ng/mL. The 10 ng/mL Be2c-VCR cells were each treated further with escalating concentrations (15–50 ng/mL) of vincristine monthly.