Fig. 1. Establishment of MT1-MMP^+/lacZ mouse strain to monitor Mmp14 transcription. (A) Schematic representation of targeting Mmp14. Exons 1-5 encoding the catalytic domain of MT1-MMP were targeted and the lacZ gene, encoding -galactosidase fused with a nuclear localization signal (NLS) was cloned in-frame with a phosphoglycerate kinase (PGK)-gpt/neo resistance gene cassette. (B) Vascular bed Mmp14 expression. Peritoneal tissue whole-cell mounts with associated segments of the musculus rectus abdominis were isolated from 3-day-old mice [MT1^+/+ (left panel) and MT1^+/lacZ (right panel)] and stained for -gal in combination with CD31. Whereas -gal staining was not observed in MT1-MMP^+/+ tissues, lacZ-positive cells were found throughout the stroma and also in association with perivascular cells in tissues of MT1^+/lacZ mouse (see below). Bars, 0.25 mm for large panels, 0.1 mm for insets. (C) Transverse sections of peritoneum and associated musculus rectus abdominus muscle from the MT1^+/lacZ mice were stained both for -gal (red) and CD31 (green). Within the vascular bed, -gal staining was confined to perivascular cells, with limited or no staining associated with the CD31-positive endothelial cells. Bar, 0.25 mm.