FIGURE 3.

Activation of MAPK by dabrafenib is not responsible for phenotypic changes during differentiation. Western blot analysis (A) and relative quantification (B) of ERK1/2 phosphorylation (p-ERK) versus total protein at increasing doses of DAB in bone marrow–derived MDSC cultures on day 4 of differentiation with IL6+GMCSF. Western blot analysis of p-ERK (C) and total cell counts (D) of bone marrow cells differentiated with indicated cytokines ± 1.5 µmol/L DAB for 4 days. For D, P values were determined by two-way ANOVA with Šidák correction post-test. Significance considered P < 0.05. Western blot analysis of p-ERK (E) and total cell counts (F) of MDSC differentiated in presence of increasing doses of MEK inhibitor Trametinib (TRAB) ± 1.5 µmol/L DAB for 4 days. For F, P values were determined by two-way ANOVA with Šidák correction post-test. Significance considered P < 0.05. G, Representative contour plot of Ly6C and Ly6G expression in CD11b⁺MHCII^neg cells expanded in presence of 1.5 µmol/L DAB and/or 3 nmol/L TRAB. For all panels, experiments were repeated three times with similar results. DAB = dabrafenib.