Figure 5.

Exogenous fibronectin matrix assembly in control and transfected GD25 cells in the presence of an anti-αV-blocking antibody. (A) Confluent cell monolayers were cultured for 2 d with 200 nM human plasma fibronectin either in the absence (a, c, e, and g) or in the presence (b, d, f, and h) of the inhibitory mAb H9.2B8 against mouse αV, used to block the endogenous αV integrins. Cells were then fixed for 10 min in 3.7% (v/v) paraformaldehyde in PBS, and the fibronectin in the matrix was stained by a polyclonal antibody followed by a rhodamine-labeled anti-rabbit IgG. Bar, 50 μm. (B) Biochemical evaluation of fibronectin matrix assembly. ¹²⁵I-labeled fibronectin incorporated into deoxycholate-insoluble matrix of cells either in the absence (−) or in the presence (+) of the αV-blocking H9.2B8 mAb was visualized by SDS-PAGE and autoradiography. The molecular weight of reduced fibronectin is shown.