Even cancers want commitment: Lineage identity and medulloblastoma formation

In this issue of Cancer Cell, Yang et al. (2008) and Schuller et al. (2008) show that Hedgehog activation in either multipotent neural stem cells or developmentally restricted progenitors causes only medulloblastomas to form. These data suggest that some stem cell-derived tumors must commit to a specific lineage in order to grow.