Characterization of primary human mammary epithelial cells (HMECs). Paraffin sections (A) or HMECs cultivated on collagen-coated cover slides (B) were stained with antibodies (markers) specific for myoepithelial (ASMA), basal/stem cells (p63), basal cells (CK5/14), and luminal cells (CK18). Immunohistochemical stainings revealed that in vivo EpCAM was expressed in basal and luminal cells of the breast, but not in myoepithelial cells. Immunofluorescence analysis revealed that HMECs stain for basal marker CK5/14, but were consistent negative for EpCAM, p63 and ASMA (n = 3). Magnification 200 ×; bars indicate 50 μm.