KIT and gastrointestinal stromal tumor: A single GIST biopsy, P5, did not show detectable expression of CK2, p-CDC37, p-KIT and KIT (Fig. 1b); although genomic analysis of this sample from a very low-risk GIST confirmed a KIT V560D mutation, the immunoblotting results raise the possibility of a biopsy sample with too low neoplastic component.