Effect of LPS on MAPK in NB-1 cells. NB-1 cells were cultured with LPS at 100 ng/ml for 30 and 60 min. The cell extracts were analyzed with immunoblotting using an antibody to p38, JNK 1/2 or the phosporylated form of p38 (pp38) and JNK1/2 (pJNK1/2). U937 was used as a positive control. A typical experimental result of three independent experiments is shown.