Effect of PMA on MAPK regulation of c-fos expression in NP cells.

<p>(<b>A</b>) <i>ERK1</i>, <i>ERK2</i>, <i>p38</i>, and <i>JNK</i> mRNA expression after exposure of NP cells to PMA (0-200 nM) for 24 h assessed by real-time RT-PCR. (<b>B</b>) Western blot analysis of ERK and p38 activation following treatment of NP cells with PMA. After 1-day of serum deprivation, NP cells were treated with vehicle (control) or 200 nM PMA. The same blots were stripped and reprobed with antibodies for total and phosphorylated proteins of ERK or p38. β-actin was detected as a loading control. (<b>C</b>) NP cells were transfected with the c-fos reporter plasmid. The transfected cells were then treated with PMA with or without the MAPK inhibitors PD98059 (PD, 30 or 50 μM), SKF86002 (SKF, 5 or 20 μM), SB202190 (SB, 1 or 10 μM), or SP600125 (SP, 1 or 10 μM) for 24 h. *<i>P</i> < 0.05 indicates significant differences between groups; n.s. = not significant.