Immunohistochemical staining of tumor cells. (a)The scFvs MIX7, MIX17 and MIX39 show significant staining of the MCF7, MDA-MB-231 and MDA-MB-468 breast carcinoma cells. No staining is observed with the negative control (irrelevant anti-SP2 antibody). (b)Staining of breast carcinoma cells in comparison with normal breast epithelial cells MCF10-2A. The selected antibodies stain the non-fixed cells more intensively than the fixed MCF7 cells, but not the MCF10-2A cells. Weak background is observed only for MIX39 scFv when it interacts with MCF10-2A cells. No staining is observed for negative control anti-SP2 antibody. (c)Staining non-fixed MCF7 cells, magnification ×60.