It is established that PREX2 can be mutated in melanoma and pancreatic ductal adenocarcinoma (Berger et al., 2012; Waddell et al., 2015), and that cancer-associated PREX2 mutations can promote both tumorigenesis in vivo (Lissanu Deribe et al., 2016) and tumor cell invasiveness (Mense et al., 2015). This evidence concerns the gene PREX2 and melanoma.