SDS-PAGE and Western blot analysis of purified APCE and rFAP. (A) Coomassie-stained reduced SDS-PAGE analysis on a 4% to 12% gradient gel. (B) Western blot of a duplicate gel to that in panel A, using a monoclonal antibody (F19) to native FAP. Although the loading in each lane (1.4 μg protein) is equivalent, the F19 antibody appears to bind rFAP to a greater extent, possibly relating to differences in glycosylation.