To examine the relationship between Golgi localization of Kit(mut) and its activity, we immuno-stained for phospho-tyrosine-721 in the kinase domain (pKit[Tyr721]) that indicates Kit’s activation.7, 8, 9 Interestingly, pKit[Tyr721] was found only in the perinuclear region in GIST-T1, GIST882 and GIST-R8 (Figure 3a, arrowheads). Here, KIT is linked to gastrointestinal stromal tumor.