Cancer progression and pathogenesis is intimately linked to extracellular matrix composition and the role of perlecan and other ECM molecules in cancer is being studied by a large number of laboratories. Since the basement membrane is the first obstacle in the way of extravasating carcinoma cells, the functions of perlecan in this process are multiple. One model system used to study perlecan expression in carcinoma cell lines is that of the MeWo/70W melanoma metastatic progression cell lines. MeWo cells are characteristically less invasive than their clonal variant cell line 70W. One lab studied perlecan expression in 27 invasive melanomas and 26 of the 27 samples showed a significant increase in perlecan message when compared to normal tissue from the same patients. They then used the MeWo and 70W cell lines to study if perlecan expression changed during treatment with neurotrophins, which can stimulate cell invasion through matrigel in vitro. The more invasive 70W cells began expressing perlecan message ten minutes after stimulation with the neurotrophins, and the MeWo cells did not produce any pln message regardless of treatment. This study took special note of the fact that perlecan upregulation occurred even before that of heparanase, an essential protein involved in the process of extravasation.