Fig. 1. Colocalization of internalized fibronectin with β1 integrins. (A-C) FN-null myofibroblasts were incubated with 10 µg/ml TR-fibronectin overnight. Cells were washed and then incubated for 12 hours in cell culture media lacking fibronectin, but containing 50 µM chloroquine. Cells were stained with an anti-β1 integrin antibody (HMβ1-1). (A) TR-fibronectin; (B) β1 integrin; (C) overlay image. (D-F) FN-null myofibroblasts were incubated with 10 µg/ml TR-fibronectin overnight. Cells were washed, and then incubated with 10 µg/ml 9EG7 at 4°C for 30 minutes. Cells were washed, and then chased for 4 hours with cell culture medium lacking fibronectin, but containing 100 µM chloroquine. Cells were then stained with a FITC-conjugated secondary antibody. (D) TR-fibronectin; (E) 9EG7 (β1 integrin); (F) overlay image. (G-I) Smooth muscle cells were incubated with 10 µg/ml TR-fibronectin and 50 µM chloroquine for 12 hours. Cells were stained using an anti-β1 integrin antibody. (G) TR-fibronectin; (H) β1 integrin (FITC); (I) overlay image. All images are optical sections collected from a confocal microscope. Scale bars: 10 µm.