Figure 1. A model of cell motility regulated by lysosomal secretion of ECM. In stationary cells, ECM is present in the environment in soluble non-adhesive form or as fibrils. For cells to transition to a motile state, they must adopt a new morphology that could be facilitated or stabilized by rapid secretion of adhesive forms of ECM. Thus, soluble ECM or proteolysed ECM fibrils could be internalized into lysosomes, cleaved into adhesive fragments by lysosomal enzymes, and resecreted at the basal cell surface adjacent to the lamellipodium to promote cell motility.