Figure 2.

EHT inhibits PP2A demethylation. A, In vitro PP2A demethylation is inhibited by EHT. In vitro assay performed with PP2A AC dimers methylated and labeled using PP2A methyl transferase, S-[methyl-³H]-adenosyl-l-methionine, and incubated with varying concentrations of EHT and 400 nm PP2A methyl esterase. Amount of ³H remaining in PP2A was assessed using liquid scintillation counting. B, EHT inhibits demethylation of PP2A in cultured neurons. Primary hippocampal neurons were incubated with varying concentrations of EHT for 4 h and harvested for Western blotting. Demethylation of PP2A (deMe-PP2A) was inhibited in a dose-dependent manner by EHT (top and graph, *p < 0.05), while total levels of PP2A (middle) and α-tubulin (bottom) were unchanged (n = 3 experiments).