Figure 5.

Covering of the substrate with fibronectin is essential for force-induced growth of focal contacts. GFP–vinculin-transfected SV-80 cells plated on poly-l-lysine in serum-free medium do not respond to pulling with a fibronectin-coated pipette by formation of focal contacts (D–F), whereas cells plated on substrate precoated with poly-l-lysine and then coated with fibronectin (fibronectin^a) produce normal focal contacts (A–C). Under standard conditions (fibronectin^b), cells were plated in serum-containing medium and then serum starved. Pulling of these cells with a poly-l-lysine–coated pipette still produces growth of focal contacts (G–I). The positions of pipette immediately after shift are indicated in B, E, and H. Images labeled before and after were taken 1–10 min before and 3–7 min after pipette shift. Bars: (B, E, and H) 10 μm; (C, F, and I) 5 μm. In each before–after pair, the pictures were taken with the same magnification.