MEK1 and MEK5 activation mediates EMT in TNBC cells. (A, B) MDA-MB-231 and (C, D) BT-549 cells were treated with dnMEK5, dnMEK1, caMEK5, and caMEK1 alone and in combination as represented in the figure. The cells were incubated for 96 hours. Immunofluorescence staining for α-actinin was performed to assess the morphology (40X magnification). The effect on ERK1/2 and ERK5 activation was evaluated. *p<0.05; **p<0.01 vs GFP control group determined by one-way ANOVA with the Bonferroni post hoc test.