(A, B) High-MITF–expressing cells (SKMEL28, SKMEL30) and low-MITF–expressing cells (A375 and SKMEL2) were transfected either with single siRNA against nontargeting control, DUSP4, and DUSP6 or co-transfected with siRNAs against DUSP4 and DUSP6 (siDUSP4+6) or DUSP4 and DUSP10 (DUSP4+10). (A, B) After 48 h, cell lysates were analyzed by Western blot (A), and DUSP10 mRNA levels were measured by RT–qPCR (B). Band intensities (A) were analyzed by ImageJ software, and the P-ERK/GAPDH and MITF/GAPDH ratios are indicated in the histogram. Data represent mean ± SEM of three independent experiments. Statistical significance was calculated against siNT for each different cell line. (A, C) Cells were treated as in (A), and cell growth was analyzed by measuring cell confluence over time. Graphs show cell growth curves normalized against time 0. Data are mean ± SEM, n = 2.