although neither protein bound to heparin , gelatin , hexosamine , or uronic acid-sepharose resins , their affinity for an invertebrate proteoglycan , their roles in sponge cell adhesion , and their peripheral membrane protein natures suggest that they may represent early invertebrate analogs of cell-associated vertebrate extracellular matrix adhesion proteins , such as fibronectin or vitronectin , or else an entirely novel set of cell adhesion molecules .
C0007577
cell adhesion
C0007578
cell adhesion molecules