PVR and neoplasm: Since tumor cells are recognized by NK cells through an interplay of activating and inhibitory ligands, we decided to evaluate the expression of CD155, CD112, MICA, MICB, ULBP1-2-5-6, PDL-1, and B7-H6 on 22Rv1, LNCaP, and DU145 prostate cancer cells (Figure 2(a) and 2(d)).