PTEN and melanoma: However, these mutations only initiate melanoma when combined with inactivation of a tumor suppressor gene, such as CDKN2A, PTEN or TP53 (Ackermann et al., 2005; Dankort et al., 2009; Dhomen et al., 2009; Dovey et al., 2009; Patton et al., 2005).