Characterisation of cell populations. The purity and phenotypic integrity of isolated primary and immortalised cell populations was confirmed by immunofluorescence. (a) Primary myoepithelial cells expressed of CK-14, CK-17, CK5/6, desmoglein (Dsg) 2, Dsg3, β4-integrin, vimentin, E-cadherin (E-Cad) and weak expression of α-smooth muscle actin (SMA). No expression of the luminal associated epithelial membrane antigen (EMA) and CK-18 was observed. (b) Isolated luminal cells expressed EMA and CK-18 along with expression of Dsg-2 and E-cadherin. (c) Isolated fibroblasts expression vimentin and a proportion of the cells expressed α-SMA but there was no expression of epithelial, macrophage of endothelial associated markers. The immortalised cell lines HB4a (luminal), MYO1089 (myoepithelial), HMFU19 (normal fibroblast) and hfff2 (fetal fibroblast) exhibited identical patterns of marker expression in comparison to their primary counterparts (data not shown).