PTEN and melanoma: In melanoma, the most common event is the methylation of CpG islands at the gene promoters, which negatively affect the genes involved in differentiation, replication, tumor suppression, and immune antigen presentation, including Ras-association domain family 1 isoform A (RASSF1A), O6-methylguanine-DNA methyltransferase (MGMT), cyclin-dependent kinase inhibitor 2A (CDKN2A), and PTEN (Esteller et al., 2001; Ehrlich, 2009; de Unamuno Bustos et al., 2018; Aleotti et al., 2021).