Cell Culture Conditions for Drug-Resistant Cells

DLD-1 cells were purchased from the Health Science Research Resources Bank (Osaka, Japan). LoVo, Colo-205 and Caco-2 cells were purchased from Riken Cell Bank (Ibaraki, Japan). HT-29 cells were purchased from DS Pharma Biomedical (Osaka, Japan). These cells were cultured in RPMI1640 medium (Sigma, St Louis, MO, USA), HamF12 medium (Sigma) or McCoy’s 5A medium (Sigma) supplemented with 10% fetal bovine serum (Gibco, Carlsbad, CA, USA), 100 μg/mL penicillin (Gibco), 100 U/mL streptomycin (Gibco) and 25 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (pH 7.4; FUJIFLIM Wako, Tokyo, Japan) in an atmosphere containing 5% CO₂.
LoVo and Colo-205 cells with acquired resistance to PD0325901 (LC Laboratories, Woburn, MA, USA) or trametinib (LC Laboratories) (LoVo/PR, Colo-205/PR and LoVo/TR) were generated as previously described [37 (link),51 (link),52 (link),53 (link),54 (link),55 (link)].