Association of RAFTK with the c-fms receptor in THP1 cells. THP1 cells (20 × 10⁶) were stimulated with 1,000 U/mL CSF-1/M-CSF for the indicated time periods. Cell lysates prepared in RIPA buffer were subjected to immunoprecipitation with either the anti-c-fms antibody (A) or anti-RAFTK antibody (B). Immune complexes were absorbed onto sepharose-A beads, washed and resolved by 7.5% SDS-PAGE, transferred to nitrocellulose membranes, and immunoblotted with either anti-RAFTK (A) or anti–c-fmsantibody (B). NRS, normal rabbit serum control.