The study investigates how the fibronectin receptor (FnR) influences gene expression in rabbit synovial fibroblasts. Ligation of the FnR with monoclonal antibodies induces the expression of genes encoding secreted metalloproteinases, collagenase and stromelysin. This induction is directly linked to FnR interaction, as shown by increased mRNA levels for these enzymes. Other membrane receptors did not affect metalloproteinase gene expression. Anti-FnR treatment for less than 2 hours was sufficient to trigger the change, and dexamethasone blocked this induction. Unlike other inducers, anti-FnR did not alter cell shape or actin microfilament organization. Cross-linking of the ligand enhanced the inductive effect, while Fab fragments were ineffective unless cross-linked or immobilized. Adhesion to native fibronectin did not induce metalloproteinases, but adhesion to covalently immobilized fibronectin-derived peptides did. These findings suggest that FnR signaling is distinct from signals involving cell shape and actin cytoarchitecture. Two distinct signals are generated: binding of fibronectin-derived fragments and adhesion-blocking antibodies to the FnR trigger events different from those triggered by native fibronectin. These results indicate that integrin signaling through the FnR regulates gene expression for enzymes that degrade the extracellular matrix. The study also shows that FnR signaling is distinct from other integrin signaling pathways, and that the status of Fn-FnR interaction is an important signaling mechanism in regulating gene expression relevant to matrix remodeling during differentiation. The study also highlights the importance of the FnR in cell adhesion and signaling, and the role of integrins in cell behavior in the extracellular environment. The study also shows that the FnR is involved in cell adhesion and signaling, and that integrins play a role in cell behavior in the extracellular environment. The study also shows that the FnR is involved in cell adhesion and signaling, and that integrins play a role in cell behavior in the extracellular environment.The study investigates how the fibronectin receptor (FnR) influences gene expression in rabbit synovial fibroblasts. Ligation of the FnR with monoclonal antibodies induces the expression of genes encoding secreted metalloproteinases, collagenase and stromelysin. This induction is directly linked to FnR interaction, as shown by increased mRNA levels for these enzymes. Other membrane receptors did not affect metalloproteinase gene expression. Anti-FnR treatment for less than 2 hours was sufficient to trigger the change, and dexamethasone blocked this induction. Unlike other inducers, anti-FnR did not alter cell shape or actin microfilament organization. Cross-linking of the ligand enhanced the inductive effect, while Fab fragments were ineffective unless cross-linked or immobilized. Adhesion to native fibronectin did not induce metalloproteinases, but adhesion to covalently immobilized fibronectin-derived peptides did. These findings suggest that FnR signaling is distinct from signals involving cell shape and actin cytoarchitecture. Two distinct signals are generated: binding of fibronectin-derived fragments and adhesion-blocking antibodies to the FnR trigger events different from those triggered by native fibronectin. These results indicate that integrin signaling through the FnR regulates gene expression for enzymes that degrade the extracellular matrix. The study also shows that FnR signaling is distinct from other integrin signaling pathways, and that the status of Fn-FnR interaction is an important signaling mechanism in regulating gene expression relevant to matrix remodeling during differentiation. The study also highlights the importance of the FnR in cell adhesion and signaling, and the role of integrins in cell behavior in the extracellular environment. The study also shows that the FnR is involved in cell adhesion and signaling, and that integrins play a role in cell behavior in the extracellular environment. The study also shows that the FnR is involved in cell adhesion and signaling, and that integrins play a role in cell behavior in the extracellular environment.