The 120FN induces collagenase activity and concomitantly decreases AP activity in PDL cells. Early passage PDL cells were cultured in serum-free medium in the absence or presence of 120FN (0.1 μM) for various time points. Cell-conditioned medium assayed by substrate zymography demonstrated a time-dependent 120FN-mediated induction of 53/58 gelatinolytic proteinase (53/58G) (A), identified as MMP-1 by Western blotting (B). This was accompanied by a time-dependent induction of MMP-1 gene expression assayed by qRT-PCR (C) and collagenase activity analyzed by FITC-collagen degradation assay on cell-conditioned medium (D). Assays on cell extract revealed that relative to control untreated cells, 120FN inhibits the time-dependent increase in AP activity (E). Data are shown as mean (+ SD) fold change relative to control baseline levels (Ct) for three experiments performed in triplicate. (*, p < 0.05; **, p < 0.01; ***, p < 0.001).