Diffuse Intrinsic Pontine Glioma (DIPG) is an incurable type of brain cancer that arises in children. Recently genomic studies unraveled that a subset of human DIPGs harbor activating mutations in ACVR1 and K27M H3.1 mutations. Here we will study the mechanisms by which ACVR1 mutations and K27M H3.1 mutations cooperate in brainstem gliomagenesis.