Western blot comparing platelet (Plt) and endothelial cell (EC) multimerin with recombinant multimerin synthesized by COS-1, HEK 293, and AtT 20 cells. Transient transfection experiments are shown in (A), and studies using stably transfected cells are shown in (B). Cell lysates and culture media from cells transfected with the empty vector (v) or the multimerin expression vector (m) were analyzed using 4% to 8%, reduced SDS-PAGE. Recently synthesized promultimerin (proM), fully glycosylated promultimerin (proM*), and the platelet multimerin subunits p-155 and p-170 are indicated.