MMP1 and melanoma: It has already been suggested that MMP-1 could be important in melanoma development through its secretion by melanoma but also by stromal cells (Woolley and Grafton, 1980; Airola et al, 1999) and, recently, it was shown that shRNA-driven MMP-1 knockdown inhibited metastasis formation in a xenograft model (Blackburn et al, 2007).