In particular, in order to to show whether an LGR5− stem cell really contributes to colon tumor initiation, it established a genetic fate-mapping system for labeling Keratin-19 (Krt19)-expressing progenitor/stem cells; this system labels a population of cells including transit-amplifying cells, progenitors and stem cells, but excludes LGR5+ stem cells [433]. The gene discussed is KRT19; the disease is colonic neoplasm.