Dual immunolocalization of latency-associated peptide (LAP) and transforming growth factor (TGF)-β in murine mammary gland. Antibodies to LAP (green) to localize latent TGF (LTGF)-β, antigen-purified TGF-β antibodies that specifically detect active TGF-β (red), and DAPI stained nuclei (blue) were visualized using tricolor digital fluorescence microscopy. (A) A section tangential to a duct; (B) a transverse and cross-section of a duct of mammary gland from a nulliparous Balb/c mouse. Colocalization of LAP and TGF-β appears yellow in certain epithelial cells (arrows). Note that certain cells have prominent LAP staining, but are not immunoreactive for TGF-β and are adjacent to cells that exhibit staining of both LAP and TGF-β. Neither stromal, myoepithelial, or endothelial (B, asterisk) cells show prominent TGF-β immunoreactivity.