Immunohistochemical analysis
Immunohistochemical analysis was performed as described previously [44]. All samples were observed under a Leica DM 2000 microscope. The percentage of positive cell area (a) was multiplied by the intensity of immunostaining (B: 0, negative; 1, weak positive; 2, positive; 3, strong positive). The final score of each slide is calculated as a × B. The final score for each slide was calculated as A×B.