Initiation of chick cell division by trypsin action at the cell surface

Abstract
Trypsin immobilized on polystyrene beads caused initiation of cell division [of chick embryo fibroblasts] which cannot be accounted for by trypsin released into the medium or into the cells. Initiation by soluble trypsin was inhibited by immobilized soybean trypsin inhibitor. Trypsin can initiate proliferation at the cell surface.