MDM2 and melanoma: Starting from the mechanism demonstrated in our previous work in follicular thyroid tumors, in which the inhibition of p90RSK triggers a decrease in cell proliferation and the activation of apoptosis through the MDM2/p53 pathway, here, we demonstrate that the inhibition of the p90RSK/MDM2/p53 pathway is critical in inducing a blockade of proliferation and apoptosis by regulating p53wt levels through the stabilization of MDM2 in selected tumors with constitutively activated MAPKs such as melanoma and lung cancer.