Doxycycline increases the expression of LPPs. A: Protein expressions of myc-tagged human LPP1, LPP2, and LPP3 in MDA-MB-231 cells with or without doxycycline (Dox) treatment at 1, 5, and 10 μg/ml (2, 10, and 20 μM) for 24 h. B: Quantification of expression levels of myc-LPP1, LPP2, and LPP3 in A. C: mRNA levels of LPP1, LPP2, and LPP3 relative to GAPDH mRNA in MDA-MB-231 cells after 24 h treatment with doxycycline. D: mRNA levels of LPP1, LPP2, and LPP3 relative to GAPDH mRNA in MDA-MB-231 cells after 1 μg/ml (2 μM) doxycycline treatment for different times. Results are means ± SD from three independent experiments. Significant differences between drug-treated and nontreated cells are shown as * P < 0.05.