Fig. 6. Blocking of β1 integrins inhibits endocytosis of fibronectin from preassembled matrix. FN-null myofibroblasts were incubated with either 30 µg/ml β1 inhibitory antibody (Ha2/5) or isotype control in suspension at room temperature for 30 minutes prior to seeding on pre-assembled TR-(A,B) or AF488 (C,D) fibronectin matrix. Cells were cultured for 24 hours at 37°C, and were then either fixed for imaging assay (A, β1 inhibition; B, isotype control) or processed for flow cytometry to quantify internalized fibronectin (C,D). The numbers over the peaks in C are the MFI of internalized AF488-fibronectin. Graph in D shows fold change relative to the MFI of endocytosed AF488-fibronectin in cells treated with isotype control IgM, which was set equal to 1 (n=4, mean ± s.d.). Scale bar: 10 µm.