To assess the role played by GSK-3β in the redistribution of p53 induced by sorafenib in the setting of HDM2 blockade, we stably transfected A375 melanoma cells with a tetracycline-inducible GSK-3β shRNA and SKMEL5 cells with a constitutively active GSK-3β (GSK-3β S9A) and examined the response of the transfectants to MI-319 and sorafenib. This evidence concerns the gene TP53 and melanoma.