In this respect, it has been previously shown that a) human erythrocytes treated with either t-BHP or H2O2 accumulate deamidated isomerized proteins in the cell membrane, which are methyl esterified ex vivo by PCMT [31]; b) human erythrocytes from G6PD-deficient subjects are particularly prone to undergo deamidation at membrane protein level, upon oxidative stress, compared to normal red cells [9]; c) melanoma cells also accumulate PCMT substrates upon UV irradiation, according to a mechanism which is mediated by an oxidation [12]. This evidence concerns the gene G6PD and melanoma.