Immunohistochemistry was performed as previously described [58 (link)]. Adenocarcinoma and adjacent normal lung tissues were fixed, dehydrated, paraffin-embedded, and sectioned. The dewaxed sections were placed in hydrogen peroxide (containing 3% methanol) for 10 min at room temperature and washed with 1 × PBS. The tissue sections were immersed in 0.01 M citrate buffer solution (pH 6.0) and heated to boiling. Following cooling, the sections were washed with 1 × PBS. Blocking solution (goat serum) was added dropwise to block for 20 min at room temperature. The purified bivalent recombinant antibody, EphA2-scFv-Fc, and the full-length antibody, EphA2-IgG1 was separately added dropwise as a primary antibody. Moreover, the human IgG1 (Shanghaiyuanye Biotechnology, Shanghai, China) was used as an isotypic control and incubated overnight at 4°C. Goat-anti-human-IgG-HRP (Abcam, Cambridge, USA) was added dropwise as a secondary antibody and incubated for 90 min at 37°C and washed with 1 × PBS at the end of the incubation. A DAB chromogenic reagent kit (Zhongshan Jinqiao, Beijing, China) was used to stain at room temperature. After hematoxylin counterstaining and dehydration, the sections were sealed with neutral gum.