Fig. 3. Metastatic lesions formed by C23-mß3 cells retain ß3 integrin expression. (A) In addition to pulmonary lesions, two mice injected with the C23-mß3 cells developed cardiac metastases. H and E staining of the lesions showed an infiltration by the tumor cells into the cardiac muscle. (B) Sections of cardiac lesions were incubated with anti-ß3 antibodies (without counterstaining) to localize the expression of this integrin. Note the intense membrane staining (arrows) indicating continued expression of ß3. The inset shows the area marked by the arrows at high magnification.