Finally, using a lineage tracing single-cell RNA sequencing (scRNA-seq) dataset based on a Ptf1a-CreER; LSL-KRas-G12D; LSL-tdTomato PDAC mouse model,21 we found that epithelial cells expressing Epcam, Ly6a/Sca-1 and Prom1/CD133 expand from early metaplastic states to full tumour cells (figure 2H,I), supporting the existence of these cells early on and throughout tumour development. The gene discussed is KRAS; the disease is neoplasm.