Using RP mice that additionally carried an enhanced green fluorescent protein (eGFP)-marked allele (Rb1fl/flTrp53fl/flRosa26Cas9-EGFP; RPC mice), we detected VGluT1-positive fibres arborizing between neuroendocrine cells from the initial stages of transformation up to the formation of small and medium-sized tumours (Fig. 2d–f). The gene discussed is SLC17A7; the disease is neoplasm.