Immunoprecipitations. Lysates from FDC-P1 cells, either untreated (−) or treated with M-CSF (+), were mixed with protein A sepharose beads and each of the antibodies indicated on the left (IP). Immunoprecipitation and immunoblotting analyses were performed as described, and three identical gels were prepared. These gels were incubated with the antiphosphotyrosine antibody 4G10, or the SHIP MoAbs P2C6 or P1D7 (IB). The positions of 145 kD and 135 kD SHIP are indicted with arrows.