In recent years, gastrointestinal stromal tumour (GIST) has emerged from a poorly understood group of mesenchymal tumours to a distinct pathological entity that has become a leading model for new therapies targeting kinases. GIST pathogenesis is driven by receptor tyrosine kinase-activating mutations most often in KIT or PDGFRA that may be sporadic or result in familial GIST syndromes. In a recent issue of The Journal of Pathology (J Pathol 2008;214:302–311), Nakai and colleagues report that mutation of the previously un-modelled tyrosine kinase II domain of KIT generates a spectrum of features very similar to that in two human GIST families. Knock-in mouse models of GIST may prove extremely useful in pre-clinical evaluation of kinase-targeted compounds and of the mechanism of drug resistance, but intriguingly it now seems clearer that the distribution of GIST in mouse models and humans is different. Copyright © 2008 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.