Fig. 4. Downregulation of mouse Sdc1 expression by siRNA blocks _vß₅-dependent cell attachment and spreading on vitronectin. FACS or immunoblot analysis for (A,F) mouse Sdc1 (mAb 281.2), (B) _v integrin subunit (mAb H9.2B8), (C) mouse Sdc4 (mAb KY8.2), (D) human Sdc1 (mAb B-B4) and (E) FcR^ecto-hS1 chimera (FITC-conjugated hIgG) expression against isotype IgG controls (red fill) in vector ^NEO (A-C), human Sdc1 (D), FcR^ecto-hS1 (E) and GPI-mS1ED (F) expressing B82L cells 48 hours after transfection with either 600 nM control (Control) or mouse Sdc1-specific siRNA (siRNA). (G) B82L^NEO empty vector-transfected control cells and B82L cells expressing human Sdc1, the FcR^ecto-hS1 or GPI-mS1ED chimera were transfected with control or mouse Sdc1-specific siRNA and seeded on wells coated with either 5 µg/ml VN alone or a mixed substratum of VN plus 60 µg/ml of antibody directed against mouse Sdc1 (281.2), human Sdc1 (B-B4) or the FcR^ecto-hS1 chimera (hIgG). Cells were incubated at 37°C for 2 hours, fixed and stained with Rhodamine-conjugated phalloidin. Bar, 50 µm.