METH preconditioning affected MEK1/2 and PP2A.

<p>(A) A representative blot showing that sublethal concentrations of METH decreased the levels of pMEK1/2 and enhanced MEK1/2 activation induced by 6-OHDA. MN9D cells were treated with METH for 24 hr, the medium was changed, and cells treated with 6-OHDA for 20 min. Lysates were collected at 0, 15 min, 60 min, and 24 hr post 6-OHDA treatment. (B) Quantification of panel A in 4 independent experiments. (C) PP2A activity assay was performed as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0024722#s2" target="_blank">methods</a> section from cells treated with various METH concentrations for 24 hr. METH pretreatment decreased PP2A activity in a concentration dependent manner, although total cellular PP2A levels were not affected. *p<0.05, **p<0.01 compared to control.