MN1 and astroblastoma: Our findings strongly support that AB-like tumors arise in the context of epigenetic and genetic changes in neural progenitors during brain development: early ependymal tumors with MN1-BEND2 from early vRG-derived cells, and MAPK pathway tumors demonstrating more classic astroblastoma histomorphology from oRG- or tRG-derived progenitors, respectively.