MMP2 and melanoma: Advances in the understanding of melanoma biology have resulted in the discovery of other promising protein biomarkers that are predictive of melanoma-specific mortality and reflective of varying aspects of tumorigenesis including resistance to antigrowth signals (p16/INK4a), limitless replicative potential (Ki-67), tissue invasion (matrix metalloproteinase-2), and sustained angiogenesis (iNOS) [3].