Studies on human melanoma have provided evidence that the plasminogen activator system and the matrix metalloproteinase (MMP) enzyme systems play an important role (Hofmann et al, 2000; Bodey et al, 2001); in particular, expression of MMP-2, an enzyme that degrades collagen IV in basement membranes, has been reported to increase in relation to malignancy of human melanocytic lesions (Väisänen et al, 1996). Here, MMP2 is linked to melanoma.