Figure 4

Erk is required for neurite outgrowth in all 3 systems whereas JNK is required only for the NP and FP, but not EP, systems. Concentrations of growth factors and PACAP used were 50 ng/ml and 100 ng/ml, respectively. (a) Dose–response treatment of (i) MEK inhibitor (U0126), (ii) JNK inhibitor (SP600125), (iii) P38 inhibitor (SB203580), and (iv) PI3K inhibitor (LY294002) on neurite outgrowth in the NP system. (b), (c) Effect of U0126 (20 μM), SP600125 (10 μM), SB203580 (20 μM), and LY294002 (20 μM) on neurite outgrowth in the FP, and EP systems, respectively. Significant differences between treatments with and without inhibitors were calculated using the paired Student’s t-test. A value of p < 0.05 was considered significant (**p < 0.01; *p < 0.05).