Expression of nidogen-1 by established epithelial, mesenchymal and carcinoma cell lines in culture. Cells were cultured for 4 days on tissue culture plastic and cell supernatants and lysates were harvested for nidogen-1 immunoblotting. The following cell lines were used: (A) Scp2 cells, (B) EPH4 cells, (C) 3T3 cells, (D) Scg6 cells, (E) TCL1 cells and (F) CID-9 cells (see Table 1 for characterization). Supernatants originating from mesenchymal and carcinoma cells contained the intact 150 kDa and the cleaved 110 kDa forms of nidogen-1, whereas none of the epithelial-derived supernatants contained nidogen-1. However, no nidogen-1 was found in the cell lysates of either the epithelial or mesenchymal cells. The positions of intact and cleaved nidogen-1 are shown on the right.