However, VEGF-A IHC showed that GADD34 mutation, either heterozygous or homozygous, had no significant effect on VEGF-A expression in medulloblastoma in Ptch1+/− mice (Figure 4G–4I, 4M), and CD31 IHC showed that GADD34 mutation, either heterozygous or homozygous, did not significantly affect angiogenesis in this tumor (Figure 4J–4L, 4N). Here, PPP1R15A is linked to medulloblastoma.