TIMP1 and breast carcinoma: We further conducted PCR experiments with matrix-embedded breast carcinoma cells MDA-MB-231 and fibrosarcoma HT1080 cells at low density (LD), 10 cells.mm−3, and high density (HD), 50 cells.mm−3 [8], and quantified the expression of MMPs from five different MMP subgroups such as collagenase (MMP 1), gelatinase (MMP 2 and MMP 9), matrilysin (MMP 7), stromelysin (MMP 3, MMP 10, and MMP 11), membrane type (MMP 14), and tissue inhibitors of metalloproteinases (TIMPs) (TIMP1, 2, 3, and 4) (Table 2).