FIG. 4.

SDS-PAGE gel autoradiograph demonstrating an 85-kDa surface protein (arrow) in ¹²⁵I-labeled Caco-2 cells (lane 1) bound by CSL and immunoprecipitated by MAb 3E2 (lane 2). ¹²⁵I-labeled RSE-1 cell surface proteins before (lane 4) and after (lane 5) incubation with CSL and precipitation with MAb 3E2 are shown for comparison. Lanes 3 and 6 were loaded with isotype control MAb-CSL precipitates from ¹²⁵I-labeled Caco-2 or RSE-1 cells, respectively. Molecular mass standards are indicated on the left in kilodaltons (myosin, 200 kDa; β-galactosidase, 97.4 kDa; BSA, 69 kDa; ovalbumin, 46 kDa; carbonic anhydrase, 30 kDa; and trypsin inhibitor, 21.5 kDa) (Amersham Pharmacia Biotech).