Melanoma cell lines (A375P and SK-MEL-2) were obtained from either the Korean Cell Line Bank (KCLB; Seoul, Korea) or YOUAI Co., Ltd. (Suwon-Si, Gyeonggi-Do, Korea). The development of BRAF inhibitor-resistant A375P melanoma cells (A375P/Mdr) was previously described (Ahn and Lee, 2013 (link)). All of the cell lines were maintained at 37°C in DMEM supplemented with 10% FCS, penicillin-streptomycin, and glutamine. The A375P/Mdr cells were further propagated in growth medium containing 1 μM PLX4720. Before their use in the experiments, the A375P/Mdr cells were maintained in PLX4720-free culture medium and subcultured at least three times. For experimental purposes, the cells were cultured in 60-mm tissue culture dishes until they reached ∼80% confluency.