(A) The results of in vitro kinase assays on the indicated immunoprecipitates obtained from NP40-solubilized Raji cells (analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis [SDS-PAGE] and autoradiography). Note major in vitro phosphorylated zones of 75-80 kD and 55-60 kD similar to those observed by Ganju et al.1 The monoclonal antibodies used were MEM-57 (CD3; negative control), MEM-78 (CD10), MEM-102 (CD48), MEM-118 (CD55), and HH2 (CDw75). (B) The results of in vitro kinase assays on CD10 immunoprecipitates obtained from the detergent lysate of Raji cells size fractionated on Sepharose 4B column (fractions 3-9; L is the unfractionated lysate). Fractions 3 and 4 represent void volume where very large complexes or particles elute; elution volume of size standards IgM and IgG was in fractions 6 and 8, respectively. (C) Same as in (B) but the lysate was fractionated by sucrose density gradient ultracentrifugation (gradient from 40% to 5% sucrose). Fraction 4 (maximum of CD10-associated kinase activity) corresponds to buoyant density of 1.05 to 1.09 g/mL. An identical profile of separation was observed in the case of CD48 and CD55 immunoprecipitates (not shown).