Fig. 3.

Arrestin is expressed in luminal and myoepithelial cells of the normal mammary duct. a Normal tissue was stained for arrestin2 (left 2 panels) or arrestin3 (right 2 panels) and counterstained with hematoxylin. Arrestin2 is expressed in both cell types, with greatest expression in myoepithelial cells, while arrestin3 is expressed at comparable levels in both cell types (myoepithelial: yellow arrow, luminal: black arrow). b and c Normal tissue was stained through immunofluorescent immunohistochemistry for arrestin2 (Arr2; b) or arrestin3 (Arr3; c) (red), cytokeratin (CK) (green) to identify luminal cells, and DAPI (blue) to identify nuclei. Arrestin2 and arrestin3 are expressed in both myoepithelial (yellow arrow) and luminal cells (white arrow). Arrestin2 displayed greatest expression in myoepithelial cells, whereas arrestin3 was expressed equally in both compartments. d Breast cancer tissue was stained for arrestin3 (red) and DAPI (blue) in the presence (left panel) or absence (right panel) of antiarrestin3