Figure 2.

Cortical neurons treated with MPP⁺ displayed alterations in all major intracellular signaling cascades. Seven-day primary cortical neurons were treated with 10, 20, and 30 μM MPP⁺ for 24 h. Equal amounts of total protein from lysates of cortical neurons were analyzed on 10% SDS-PAGE and immunoblotted with antibodies specific for phosphorylated forms of AKT (A), p38 MAPK (B), ERK1/2 (C), JNK/SAPK (D), p70S6K (E), as well as for the phosphorylated forms of p70S6K substrate S6RP (F). To ensure equal loading membranes were re-probed against AKT, p38 MAPK, ERK1/2, JNK/SAPK, p70S6K, and S6RP, respectively. Quantification of the results was performed by scanning densitometry. Bars in the graph depict mean ± s.e.m. Note that MPP⁺-treatment changed the phosphorylation status of all the major signaling kinases examined in a concentration dependent manner. ^**P ≤ 0.01, ^***P ≤ 0.001.