Stimulation of the protein synthesis by fibronectin is specific for untransformed fibroblastic cells

: In the preceding paper, we showed that fibronectin (FN) in solution has the ability to stimulate protein synthesis in NIH-L1 fibroblastic cells. We show here that FN stimulated protein synthesis also in other normal fibroblast cell lines, WI-38 and BALB/3T3, but did so only slightly in their transformed cell lines, L1-4NQOH10, WI-38 VA-13 and KN(7)8; and in rat hepatocytes in primary culture and rat liver epidermoid cells (GR-1) it hardly affected the synthesis. Augmentation of the protein synthesis rate was not attributable to stimulation of collagen synthesis. This stimulatory activity of FN was enhanced remarkably by proteolytic digestion of FN with trypsin.