Furthermore, pro-oncogenic properties of the MK5/PRAK-Δex8 protein would also explain the gene dosage effect observed in the skin carcinogenesis model using the Δex8 mice, where +/Δex8 mice had a tumor free survival rate which was clearly intermediate between the survival rates of Δex8/Δex8 and +/+ mice [6]. This evidence concerns the gene MAPKAPK5 and neoplasm.