Figure 4.

Optic glioma formation and growth is partly determined by the effect of the germline Nf1 gene mutation on astrocyte RAS effector activation and proliferation. (A) Astrocyte proliferation was increased by 3.2- to 4.0-fold following Cre-mediated Nf1^flox inactivation (Cre) in Nf1^G681X/flox and Nf1^neo/flox astrocytes, but only by 1.3-fold in Nf1^G848R/flox astrocytes. Normalization is relative to control Nf1^flox/flox astrocytes (LacZ infection) (n > 3 samples per genotype). Data are represented as means ± s.e.m. (*P < 0.05; one-way ANOVA with Dunn's multiple comparison test). Immunostaining with pAkt^Ser473 (B) pERK^{Thr202/Tyr204} (C) and pS6^Ser240/244 (D) antibodies revealed a greater percentage of pAkt^Ser473, pERK^{Thr202/Tyr204} and pS6^Ser240/244-immunoreactive cells in the optic nerves of neo^CKO (pAkt^Ser473: 9-fold increase, pERK^{Thr202/Tyr204}: 7.4-fold increase, pS6^Ser240/244: 2.8-fold increase) and R681X^CKO (pAkt^Ser473: 10.4-fold increase, pERK^{Thr202/Tyr204}: 7.1-fold increase, pS6^Ser240/244: 3.3-fold increase) optic nerves relative to Nf1^flox/flox littermate controls (CTL). A minimum of four animals per genotype was assayed. n.s., not significant. Scale bars: 100 µm. Data are represented as means ± s.e.m. (*P < 0.05, ***P < .001; one-way ANOVA with Bonferroni post-test).