Knocking down RSK2 or MSK1 expression inhibits A431 anchorage-independent cell growth and proliferation. A431 cells stably expressing sh-mock, sh-RSK2, sh-MSK1 or sh-RSK2/sh-MSK1 were evaluated for colony growth under anchorage-independent conditions (A). Proliferation of A431 cells stably expressing sh-mock, sh-RSK2, sh-MSK1 or sh-RSK2/sh-MSK1 was measured by MTS assay at the indicated time point (B). Data are shown as mean values ± S.D. obtained from triplicate experiments. Significant differences were evaluated using one-way ANOVA and the asterisks indicate a significant effect (*, p < 0.05; **, p <0.01).