Fig. 2

Down-regulation of KOR protein in HCC. a Representative immunohistochemical staining of KOR protein expression in 174 HCC tissue samples (magnification ×200). Absent or weak staining was defined as negative expression, while moderate or strong staining was defined as positive expression. b The presence of KOR staining in HCC tissues and corresponding non-tumour tissues. c, d Kaplan-Meier analysis for overall survival (OS) and recurrence-free survival (RFS) of 174 HCC patients in correlation with KOR expression. The OS and RFS rates were significantly decreased in KOR-negative HCC patients compared with those in the KOR-positive group (both P < 0.001). The duplicated images in Figs. 2, 3 and Additional file 1: Figure S1 represent the same experiment