['to', 'represent', 'selected', 'domains', 'of', 'the', "cell's", 'plasma', 'membranes,', 'in', 'that', 'only', 'certain', 'plasma', 'membrane', 'glycoproteins', 'are', 'shed', 'as', 'part', 'of', 'membrane', 'fragments.', 'The', 'glycoproteins', 'released', 'as', 'nonparticulate', 'molecules', 'into', 'the', 'extracellular', 'environment', 'failed', 'to', 'exhibit', 'these', 'quantitative', 'and', 'qualitative', 'differents.', 'Current', 'studies', 'are', 'underway', 'to', 'correlate', 'to', 'unigue', 'biological', 'activities', 'associated', 'with', 'B16-F10', 'membrane', 'fragments', 'with', 'these', 'unique', 'bands.']