Mommy - where do tumors come from?

Identification of the cell of origin of cancers is a hot topic, and recently no fewer than five groups have addressed this question for basal cell carcinomas (BCCs) of the skin. In this issue of the JCI, Grachtchouk et al. present evidence from engineered mouse models that at least some BCCs can arise from hair follicle tissue stem cells. Although these cells sustain oncogenic mutations while in the stem cell niche, they may have to leave that stem cell niche to become tumor cells.