Detection of VEGF by immunohistochemical staining. (A and B) Tumor (original magnification × 40); (C and D) lymph node (original magnification × 200); and (E and F) spleen (original magnification × 100) from mice with vIL-6–producing tumors. Sections were stained with (A, C, and E) rabbit anti-VEGF Ab or (B, D, and F) control rabbit IgG. Sections were reacted with diaminobenzidine peroxidase substrate and counterstained with hematoxylin. Diffuse staining of the tumor cells (A) and focal staining of lymph node (C) and splenic white pulp area (E).