By isolating intestinal crypts or single multipotent adult stem cells, embedding them in a gel scaffold (often Matrigel, an Engelbreth-Holm-Swarm tumour extract), and adding externally defined growth factors such as epidermal growth factor (EGF), R-spondin and Noggin, 3D enteroids can be generated with organized crypt and villus domains containing many of the differentiated cell types encountered in the gut epithelium in vivo1. Here, EGF is linked to neoplasm.