High levels of syndecan-1 accumulate in the media of cells expressing soluble syndecan-1 ectodomain.

Immunodot assays using antibody 281.2 were performed on media isolated from cell cultures 24, 48, and 72 hours after introduction of cells. Soluble syndecan-1 (sSyn-1) is detected in high levels from both clones (sSyn-1.2 and sSyn-1.10). Cells transfected with full-length syndecan-1 (Syn-1) express syndecan-1 at the cell surface and produce low levels of soluble syndecan-1 ectodomain because of constitutive proteolytic shedding. The data represent means of triplicate samples ± SE.