Immunoprecipitation of recombinant human β3 integrin expressed in transfected CHO cells. Detergent extracts of mock-transfected CHO cells and positive transfectants were incubated with anti-β3 MoAb P37. The immunoprecipitates were resolved by 7% SDS-PAGE under reducing conditions, transferred to nitrocellulose, and visualized with an MoAb to αv (VNR139), reacting with hamster αv, and MoAb 4D10G3, reacting exclusively with human β3. The strong band visualized with goat antimouse IgG conjugated to horseradish peroxydase corresponds to precipitated MoAb P37. Lane 1, total platelet lysate serving as a positive control; lane 2, CHO β3-wild-type cells; lane 3, mock-transfected CHO cells; lane 4, CHO β3-met cells; lane 5, CHO β3-pro cells. The position of αv and β3 is indicated.