Serum-starved BM macrophages were exposed to increasing numbers of apoptotic (A
) or necrotic (B
) Jurkat cells for 15 min. Apoptotic or necrotic cells were added to macrophages at a cell to macrophage ratio ranging from 1:64 to 1:1 in 2-fold increments. Nonadherent cells were removed by rinsing, and macrophage lysates were probed with anti-active p38 or anti-active JNK antibody. Equal loading was confirmed by Ponceau S staining of blotted proteins as well as probing for total p38 (supplemental Fig. S3
) or JNK (not shown). Apoptotic and necrotic cells alone contributed no active p38 and JNK in these experiments.