ACVR1 and diffuse intrinsic pontine glioma: Screening mutant and wild-type DIPG cultures with a range of pyrazolo[1,5-a]pyrimidine- and pyridine-based ALK2 inhibitors demonstrated differential effects on cell viability, recapitulating genetic knockdown with shRNA, and prolongation of survival in orthotopic patient-derived xenograft models of DIPG.