KIT and oncocytic adenoma: Miliaras et al., showed that intercalated cells of renal collecting tubules are CD117-negative whereas proximal convoluted tubules (PCT) are CD117-positive.[16] These findings imply that a mechanism of c-kit activation may be involved in oncocytoma and ChRCC tumorigenesis and conversely c-kit inactivation may be implicated in c-kit-negative renal epithelial tumors.