PTEN and melanoma: Furthermore, the loss of PTEN was found to be associated with melanoma progression, apparently due to boosted superoxide anion production consequential to the constant activation of Akt, and the loss of function for the alleles of the gene encoding for the protein MC1R is correlated with an increased risk to develop melanoma due to increased oxidative stress in melanocytes resulting from the failure to respond to α-MSH [88,89].