Activation of JNK and p38 kinase upon chemokine stimulation. (A) L1.2 and CCR5-L1.2 cells were stimulated with MIP1β and were immunoprecipitated with JNK antibody and subjected to in vitro kinase assay using GST–c-jun (1-79 amino acids) as substrates. The experiment was repeated three times with similar results. (B) CCR5-L1.2 cells were stably transfected with vector control pcDNA, RAFTK^wt or RAFTK^m457. The transfectants were stimulated with MIP1β (25 nmol/L) for 15 minutes and the cells were lysed, immunoprecipitated with JNK antibody, and subjected to kinase assay. (C) CCR5-L1.2 cells were stimulated with MIP1β or anisomycin and cell lysates were immunoprecipitated with p38 kinase antibody. The immune complexes were subjected to kinase assay using MBP as a substrate.