Fig. 3: Focal adhesion-related protein complexes are major and common humoral antigens in tumor microenvironments.

a GO enrichment analysis of the eight identified protein antigens. b–i Fluorescent immunocytochemistry of the identified protein antigens (green) along with focal adhesion kinase (FAK) (red) onto a human gastric cancer cell line MKN1. The blue color represents Hoechst nuclear staining. The white bars indicate 20 μm. The white arrowheads indicate representative hot spots of colocalization between protein antigens and focal adhesions (only in b–f). Similar colocalizations were reproducibly observed in all analyzed cells with formations of visible focal adhesions (only in b–f). The same immunocytochemical staining was also performed onto another human gastric cancer cell line GSU, obtaining similar results (Supplementary Fig. 4). j Co-immunoprecipitation experiments of the FAK complex. The upper and lower panels at the left side show co-IP using anti-FAK antibody for MKN1 and anti-GRB7 antibody for GSU, respectively, followed by immunoblots using the indicated antibodies. The right-side panels show co-IP using anti-FAK antibody for A549, a lung adenocarcinoma cell line, and HEK293 transfected with GRB7-myc/His construct, respectively, followed by immunoblots using the indicated antibodies. Co-IP experiments were conducted at least twice.