Figure 1.

Fibronectin matrix stability depends on the continuous presence of fibronectin. Fibronectin-null cells were grown to 80% confluence on dishes coated with vitronectin (A) or collagen (B) and then incubated with 20 nM FITC-conjugated fibronectin. After an overnight incubation, cells were either processed for immunofluorescence (Pulse, A) or were washed and then incubated with either 20 nM unlabeled fibronectin (Chase: +FN; G and H) or an equivalent volume of PBS (−FN; C–F) for the indicated times. Cells were then fixed and permeabilized. FITC-fibronectin staining and the corresponding phase pictures are shown. Bar, 10 μm.