[Perspective] Tracking the origins of tumorigenesis
Cancer arises through mutations that transform normal cells into cells that proliferate in an uncontrolled manner, form a tumor, invade the underlying tissue, and then metastasize to distant organs (1). Although the genetic events required to induce tumor formation are relatively well known (2), the additional early downstream molecular events that are required to reprogram normal cells into cancer cells are still poorly understood. On page 464 of this issue, Kaufman et al. report the development of an elegant transgenic reporter system that allows the early steps of tumor initiation to be tracked in situ. They find that oncogene-expressing melanocytes are reprogrammed into neural crest–like progenitors before progressing into invasive tumors (3). Authors: Soufiane Boumahdi, Cédric Blanpain