<p>Representative immunoreactivity is shown on serial sections of a pulmonary SCC. Slides were subjected to heat induced epitope retrieval (HIER) conditions using buffers of differing pH, followed by an optimized IHC protocol using 55B11: primary antibody reagent negative control (A), Tris buffer (B), citrate buffer (C), and EDTA buffer (D). VEGFR2 immunoreactivity in endothelial cells lining blood vessels (black arrows) and membranous (black arrowheads), cytoplasmic, and nuclear compartments of malignant tumor cells was found to be most optimal with EDTA buffer (panel D). Slides were counterstained with hematoxylin. Original magnification ×200. Scale bar: 50 µm, applicable to all panels.</p
