The importance of proper endocytic FN turnover for cell movement is exemplified by a study that reported that in migratory fibrosarcoma cells, once assembled FN fibrils are rapidly cleaved, internalized by endocytosis, degraded intracellularly by lysosomal proteases, and re-secreted via the late endosomal/lysosomal pathway to promote cell adhesion and motility (Humphries and Ayad, 1983; Sung and Weaver, 2011). Here, FN1 is linked to fibrosarcoma.