Little is known about miRNA-424-5p in melanoma, while studies have suggested that miRNA-20b-5p may inhibit tumour metastasis via regulation of the PAR-1 receptor in melanoma cells [73], and miRNA-21 may regulate melanoma cell proliferation, migration, and apoptosis through the ERK/NF-κB signalling pathway by targeting SPRY1, PDCD4 and PTEN [74, 75]. This evidence concerns the gene PDCD4 and melanoma.