GTE pre-incubation protects primary human osteoblasts against oxidative stress. Osteoblasts were pre- incubated with GTE for 4 h, afterwards oxidative stress was induced with 1 mM H2O2 for the next 1 h. LDH release (A) and viability (B) were measured photometrically (N = 3, n = 3). ROS production was measured via flow cytometry, whereby the 11.9% present the DCFH positive cells (C, D). Osteoblasts were pre-incubated with GTE for 1 h and subsequently for 15 min. with 1 mM H2O2 (N = 3, n = 2). Bars represent mean ± s.e.m. of three independent experiments. *p < 0.05, ***p < 0.001 (ANOVA/Bonferroni), DCFH (2`7`- dichlorofluorescein).