Immunostaining of tumor tissue samples (T18). Thin sections of paraffin-embedded tissue reacted with monoclonal antibody 7H12, which recognizes β-tubulin classes I + IV (A); monoclonal antibody 7B9, which recognizes β-tubulin class II (B); and monoclonal antibody TUJ1, which recognizes β-tubulin class III (C). (D) No primary antibody. In these panels red staining indicates a positive reaction, and blue staining indicates no reactivity. Note that (C) showed no reactivity with tumor cells, only with background stromal tissue.