LGR5 and colorectal cancer: In colorectal cancer patient-derived organoids, the use of CRISPR-Cas9 gene editing to insert cassettes into the LGR5 locus – a biomarker of adult stem cells in certain tissues – enabled lineage tracing and revealed that LGR5+ cells survive for long time periods, producing progenies that are capable of forming tumours (Cortina et al., 2017; Shimokawa et al., 2017).