PTEN and Hydrocephalus: EGFRvIII; nes-cre; Pten+/− mice developed signs of spinal (focal paralysis) rather than brain disease (hydrocephalus or seizures) and showed a reduction in survival time compared with mice just carrying the EGFRvIII and nes-cre alleles (median age 13.0 vs 41.1 weeks, p < 0.001, log-rank test; Fig. 7e).