KIT and mastocytosis: On the other hand, activated c-KitR has been implicated in the pathogenesis of multiple human malignancies; moreover, c-kit aberrations, leading to a constitutively activated form of c-KitR in the absence of its ligand, have been identified in several angiogenesis-dependent diseases, such as GISTs [35, 36], mastocytosis [37], acute myeloid leukemia [38], small cell lung cancer [39], and prostate cancer [40].