The expression of MMP-1, 3, TIMP-1, ratio of MMP-1/TIMP-1, MMP-1 activity, and PAI-1 in fibroblasts. A) MMP-1 released into cell culture media after PDGF, DHLA, and/or NAC incubation. B) MMP-3 released into cell culture media after PDGF, DHLA, and/or NAC incubation. C) TIMP-1 in cell culture media after PDGF, DHLA, and/or NAC incubation. D) The MMP-1/TIMP-1 ratio in NL and SSc dermal fibroblasts. E) MMP-1 activity was significantly higher in NL dermal fibroblasts compared to SSc cells. PDGF significantly increased MMP-1 activity in both NL and SSc cells. Both DHLA and NAC appeared to increase MMP-1 activity significantly in SSc dermal fibroblasts when stimulated by PDGF. F) PAI-1 released from both NL and SSc dermal fibroblasts in the presence of PDGF. Results are expressed as mean ± S.E. and p < 0.05 was considered significant. NL: normal; BM: basal medium; NS: non-stimulated.