These results are consistent with our clonal analysis, suggesting that multipotent Notch1+ tumour cells can give rise to heterogeneous lineages comprising distinct cell types, such as differentiated cells (Lyz1+), and raise the intriguing possibility that Notch1+ tumour cells might generate Lgr5+ tumour cells, thus contributing to tumour growth and propagation. The gene discussed is LGR5; the disease is neoplasm.