Fig. 7.

Effects of MAPK inhibitors on TH induction by aFGF and its coactivators. A, Cultures of E14 striatal neurons were preincubated for 1 hr with various concentrations (1–75 μm) of apigenin, a specific inhibitor of MAPK, before the addition of 10 ng/ml aFGF plus individual or combined coactivators (200 nm TPA, 20 μm DA, and 0.25 mmIBMX/50 μm forskolin) or coactivators only. On the next day the cultures were fixed and stained immunocytochemically for the presence of TH. Then the percentage of TH-positive neurons was counted (at 10× magnification) in 50% of all microscopic fields.B, The same procedures were repeated as inA, using various concentrations (1–25 μm) of PD98059, a specific inhibitor of MAPK and its upstream kinase, MAPK kinase (also known as MEK).