CXCR4 and oncocytic adenoma: Additionally in the analysis of benign kidney tissue, we evaluated expression within benign kidney lesions of various histological geneses: Oncocytomas as benign tumors of epithelial origin showed significantly higher cytoplasmic CXCR4 expression than ccRCCs, whereas such a difference could not be shown for angiomyolipomas as tumors of mesenchymal origin.