FIGURE 6.

Trk inhibitor blocks neurotrophin-dependent phosphorylation of Trk receptor and attenuates ERK phosphorylation and BTIC survival. BTIC-12 (A and B) and BTIC-48 (C and D) were withdrawn of growth factors overnight and treated with the MEK inhibitor PD0325901 (100 nm) or Akt inhibitor MK2206 (1 μm); 1 h later cells were added with BDNF and NT3 (100 ng/ml) for 10 min. Then cells were lysed, and p-ERK and p-Akt levels were measured (A and C). The effects of these inhibitors on cell viability were also measured in the presence or absence of a single treatment of PD0325901 (100 nm) or MK2206 (1 μm) and neurotrophins NGF, BDNF, and NT3, and EGF for 4 days (B and D). * indicates statistical significance between neurotrophin and EGF treatment compared with untreated; ** shows the difference between neurotrophin treatment with and without MEK and Akt inhibitors; and *** indicates the difference between EGF treatment with and without MEK and Akt inhibitors (p < 0.05). UT, untreated.