SPP1 and cutaneous melanoma: The selected candidate proteins in this study have been recently assessed in UM (i.e. OPN, MIA, CEACAM-1, MIC-1, and HSP27) [9, 14–23, 30, 32, 33] and/or cutaneous melanoma [29, 35, 37] as well as other cancers [31, 34, 36] (i.e. SPON1 and POSTN) by either ELISA or immunohistochemistry or other techniques.