Immunohistochemical pictures of frozen tissue sections, double-stained for CD4 (brown) and sialoadhesin (blue) (A and B) and for β₂M^b (brown) and sialoadhesin (blue) (C and D) in livers from tumor-bearing mice (d43) 20 days after ADI treatment. (A and C) Areas of portal vein (original magnification × 160); (B and D) areas of parenchyma (original magnification × 160).