A, Western blots were used to analyze the induction of c-Jun and the activation of MAPK pathways, ERK1/2, p38 and JNK, by TPA and GnRH. Whole cell extracts following treatment with 100 nM TPA or 100 nM GnRH for 10, 30, or 60 minutes, were run on the gel and after transfer, membranes were probed for c-Jun, or phosphorylated forms of ERK1/2, p38 and JNK as indication of activation. The membranes were stripped and re-probed with antibodies for β-tubulin or total, ERK1/2, p38 and JNK to indicate even loading.