Immunohistochemistry of ENO1, ENO2 and ENO3 in Normal Human Breast. Formalin-fixed, paraffin-embedded human breast biopsy specimens were immunohistochemically stained with specific antibodies to ENO1 (A and B) or ENO2 (C and D). Color development was performed via an HRP-linked secondary antibody with diaminobenzidine as the enzyme substrate, giving light to dark brown color in regions exhibiting ENO protein expression. ENO1 shows staining in both myoepithelial and epithelial cells of the breast lobules and ducts whereas ENO2 shows expression mainly in the myoepithelial cells with a slight staining in the epithelial cells of breast lobules and ducts. Magnification 100× for A and C; 200× for B and D.