Fig. 1.

Doxycycline increased the dephosphorylation of exogenous [³²P]LPA (ecto-activity) in various cell lines. A: Treatment with doxycycline at 1 μg/ml (2 μM) for 24 h increased ecto-LPP activity in HEK293 cells. B: Treatment with doxycycline for 24 h increased ecto-LPP activity in human MDA-MB-231 breast cancer cell line. C: Treatment with doxycycline for 24 h increased ecto-LPP activity in human MCF-7 breast cancer cell line. D: Treatment with doxycycline for 24 h increased ecto-LPP activity in mouse 4T1 breast cancer cell line. E: Treatment with doxycycline for 48 h increased ecto-LPP activity in nontransformed human mammary epithelial MCF10A cell line. F: Ecto-LPP activity of MDA-MB-231 cells at different time points after treatment with doxycycline (Dox) at 1 μg/ml (2 μM) and pan MMP inhibitor marimastat (Mari) at 5 μM. Results are means ± SD from three independent experiments. Significant differences between drug-treated and nontreated cells are shown as * P < 0.05 and ** P < 0.01.