Fig. 4

iHBFC^CD26 convey a ductal-like differentiation of myoepithelial cells. a Images showing FACS sorted CD271^high/MUC1^low breast primary myoepithelial cells in co-culture with iHBFC^CD105 (left) and iHBFC^CD26 (right), fluorescently labeled for K17 (white) and K14 (not shown) by immunocytochemistry. K14 staining was used as a guide in image analysis to identify K14⁺ myoepithelial cells prior to measuring myoepithelial K17 staining intensity. Box plot shows interquartile range and median of K17 mean fluorescence in arbitrary units (AU) of three biopsies (whiskers indicate upper and lower quartiles; asterisk indicates significance at p < 0.05 by Kruskal-Wallis rank-sum test). b Primary myoepithelial/fibroblast co-cultures (iHBFC^CD105 (red), iHBFC^CD26 (gray)), were single cell suspended and stained for CD271 before analysis by FACS. Histogram shows cell count normalized to mode versus myoepithelial CD271 staining intensity in arbitrary units (AU) of a single biopsy (left) and box plot shows the interquartile range and median of the mean of CD271 fluorescence intensity relative to iHBFC^CD105 in arbitrary units of three biopsies (right; whiskers indicate upper and lower quartile, asterisk indicates significance at p < 0.05 by Kruskal-Wallis rank-sum test). c Schematic showing the experimental outline (left): primary CD271⁺ myoepithelial cells are plated onto confluent fibroblast feeders (passage 1 co-culture, Ps1), from which myoepithelial cells are isolated and then re-plated onto new fibroblast feeders (passage 2 co-culture, Ps2). Dot plot (right) shows normalized myoepithelial CD271 fluorescence in arbitrary units (AU) with mean values and standard deviations indicated by vertical bars as measured by FACS of 2250 cells in passage 1 and 2 co-cultures grouped according to feeder (iHBFC^CD105 (red) or iHBFC^CD26 (gray)). Note that the myoepithelial phenotype shifts as a consequence of a switch between fibroblasts (asterisk indicates significance at p < 0.05 by nested t test)