PVR and renal cell carcinoma: To this aim we firstly evaluated the basal expression of NKG2D (MICA, MICB, ULBP1, 2, 3, 5, 6) and DNAM-1 (PVR and nectin-2) ligands on A-498 and Caki-2 RCC cells by immunofluorescence and cytofluorimetric analysis.