Shimokawa et al.53 recently demonstrated that LGR5+ carcinoma cells differentiated into both LGR5+KRT20− and LGR5−KRT20+ daughters, and that selective ablation of LGR5 (using a CRISPR-Cas9 system) resulted initially in tumour regression followed by re-expression of LGR5 and recovery of tumour growth. The gene discussed is KRT20; the disease is carcinoma.