Anti-Smad2 Antibody - Western Blot. Western blot of affinity purified anti-Smad2 to detect over-expressed Smad2 in COS cells (arrow). Lane C shows mock infection of COS cells with lentiviral vector alone. Lane S2 shows detection of Smad2 in lysates of COS transfected with Smad2. Lane V contains lysates of MDA-MB231 cells treated with vehicle; the next lane contains lysates of MDA-MB231 cells treated with TGF?. Low levels of staining in control lanes correspond to detection of endogenous Smad2. Preincubation of the antibody with immunizing peptide (data not shown) completely blocks specific band staining. The blot presented is askew relative to the molecular weight markers. The expected MW for Smad2 is 52 kD. The membrane was probed with the primary antibody at a 1:2500 dilution. Personal Communication Kathleen Flanders, CCR-NCI, Bethesda, MD.