Diverse expression of NKG2D ligands in non-neoplastic prostate tissue. The upper panels show immunohistochemistry for ULBP1 (A), ULBP2/6 (B), and ULBP4 (C) as positive, and the lower panels for MICA/B (D), ULBP3 (E), and ULBP5 (F) as negative. Scale, 100 μm.