Fig. 5.

Sustained MEK inhibition decreases Nf1 mouse optic glioma volume and proliferation. (A) Western blot demonstrates ERK^T202/Y204 phosphorylation at 0, 2, and 12 h following a 5-day treatment of PD901 (5 mg/kg, once a day; n = 3 mice per time point). (B) FMC mice treated with 5 mg/kg PD901 twice daily (n = 8) for 4 weeks have reduced optic glioma tumor volumes (scale bar, 1000 µm, arrow, tumor region) and proliferation (%Ki67⁺ cells), comparable to Nf1^flox/flox (wild-type [WT], n = 6) mice. (C) PD901-treated mice have reduced ERK activation (%pERK⁺ cells) and S6 activation (%pS6⁺ cells) compared with vehicle-treated mice (n = 6). Scale bar, 50 µm. Arrows and insets denote representative immunopositive cells. *P < .05. Bar graph denotes mean ± SEM; ns, not significant.