Effect of PD98059 on IL-3 mediated neuroprotection against Aβ toxicity. Primary cortical neurons were pre-treated with 20 μM PD98059 for 30 min before addition of 5 nM IL-3. One hour after addition of interleukin, cells were exposed to 10 μM Aβ and incubated for an additional 24 h. Then the cells were used for Western blot and viability analysis. (A) Immunoblot analysis using phosphorylation-specific antibodies (p-ERK 1/2, p-Jak2, and p-Akt). (B). Normalized densitometry scans of proteins (mean ± SEM, *, #, p < 0.05). The student's t-test was used for the statistical analysis of significance of difference. (C). Neuronal death was determined by MTT colorimetric assay and Tripan blue exclusion. Data represent mean ± SEM for three independent experiments (with a minimum of 4–5 wells per group for each experiment).