Electrophoresis and immunoblot analysis of the expressed proteins. FGF1 (lane 1), FGF1-myc-(His)6 (lane 2), FGF1-3xFLAG-(His)6 (lane 3) and FGF1-V5-(His)6 (lane 4) were expressed by E. coli and semipurified by heparin-Sepharose affinity chromatography. The eluate was subjected to SDS-PAGE and stained with CBB (a). After electrophoresis, the separated proteins were transferred to nitrocellulose membranes and immunoblotted using monoclonal anti-FGF1 (b), anti-His (c), anti-myc (d), anti-FLAG (e) or anti-V5 (f) antibodies. Positions of the molecular weight markers are indicated at the left of each panel in kDa.