ATOH1 and medulloblastoma: CD15-positive CSCs identified in medulloblastomas revealed the existence of a certain population of CD15-positive cells expressing the TFs atonal bHLH transcription factor 1 (ATOH1), suggesting that the ability to propagate tumors may not only be restricted to a rigorous “stem-like” state but instead may result from cycling fate-restricted progenitors that give rise to tumor initiation and growth (Schuller et al., 2008; Yang et al., 2008; Ward et al., 2009; Vanner et al., 2014).