Figure 6.
Immunoprecipitation of extracellular matrix proteins expressed by mesothelial cells. Mesothelial cells were labeled with [35S]methionine and lysed, and the cell lysate was immunoprecipitated with polyclonal antibodies to fibronectin (lane 2), laminin (lane 3), vitronectin (lane 4), type I collagen (lane 6), type III collagen (lane 7), and type IV collagen (lane 8) or a MAb against the β1 integrin subunit, P5D2 (lane 10). Negative controls were normal rabbit IgG (lane 1), normal goat IgG (lane 5), and normal mouse IgG (lane 9). The immunoprecipitates were separated on a 7.5% SDS-PAGE under reducing conditions, and the gels were dried and then exposed to Kodak X-Omat autoradiograph film. Molecular weight standards were myosin (220 kd) and phosphorylase b (97.4 kd).