MMP-2/laminin-5 in mammary glands of adult wild-type and PR-A mice; laminin immunostaining in PR-B transgenics. In situ localization of MMP-2 and laminin-5 in mammary glands of adult wild-type (WT) and PR-A transgenics, and laminin staining in PR-B transgenics. (a) MMP-2 and laminin-5 were detected in fixed frozen sections of mammary glands, using an indirect immunofluorescence assay, as described in the text. Blue, 4',6-diamino-2-phenylindole (DAPI) staining of the nuclei; green, fluorescein isothiocyanate staining corresponding to immunoreactive latent MMP-2; red, Texas Red staining corresponding to immunoreactive laminin-5. Staining in glands from WT mice and in normal structures derived from PR-A mice showed continuous laminin-5 staining and the presence of MMP-2 in the periepithelial stroma. In aberrant structures derived from glands of PR-A transgenic mice, however, staining for both laminin-5 and latent MMP-2 was lost (right panels). Top left, mammary duct from wild-type mouse; bottom left, normal duct from PR-A transgenic mouse; top right, duct from PR-A transgenic mouse containing both normal and morphogenetically disturbed epithelium; bottom left, aberrant structure in PR-A transgenic mouse. (b) Laminin staining (green) in a mammary gland derived from a PR-B transgenic mouse shows that it circumscribes the epithelium as in the WT control. Nuclei were counterstained with DAPI (blue).