Tissue sections (3 µm) were obtained from paraffin-embedded blocks, as previously described (13 (link)). The slides were deparaffinized, rehydrated with ethanol and heated in a 10 mM citrate buffer (pH 6.0) by microwave for 7 min to retrieve antigens. Endogenous peroxidase was blocked with 3% hydrogen peroxide for 15 min at ambient temperature. The slides were then washed with tris-buffered saline and incubated with a primary rabbit polyclonal antibody against UBE2B (1:100 dilution; GeneTex, Inc.) for 1 h. A ChemMate EnVision kit (DAKO; Agilent Technologies, Inc.) was applied to detect the primary antibody. Tissue sections incubated with rabbit IgG in place of primary antibody served as negative controls. A total of two pathologists who were blinded to this study examined the UBE2B expression and scored the intensity and distribution with a multiheaded microscope to reach a consensus on the histology (H)-score using the following equation: H-score=ΣPi (i+1) where i represents the intensity of stained tumor cells, and Pi is the percentage of stained tumor cells, ranging from 0 to 100%. Tumors with H-scores higher than the median value for all examined samples were classified as having high UBE2B expression levels.