Determination of the antioxidant response following gamma radiation exposure of in vitro lung vascular networks (flow-adapted endothelial cells) and LGM2605 (synthetic secoisolariciresinol diglucoside (SDG)) treatment. FAECs were exposed to 0 Gy, 0.25 Gy, or 0.5 Gy gamma radiation and treated with 0 µM, 50 µM, or 100 µM LGM2605 30 min following radiation exposure. Cells were harvested 24 h post radiation exposure and mRNA expression of HO-1 (A), NQO1 (B), and GSTM1 (C) was determined using qPCR. Levels of target gene mRNA were normalized to 18S ribosomal RNA and the values are expressed as mean fold change from FAECs exposed to 0 Gy and treated with 0 µM LGM2605. Data are presented as mean ± SEM. # shown in figures indicate significant differences from FAECs exposed to 0 Gy gamma radiation and treated with 0 µM LGM2605 (# p < 0.05; ## p < 0.01; ### p < 0.001; #### p < 0.0001). Asterisks shown in figures indicate significant differences from FAECs exposed to 0 Gy, 0.25 Gy, or 0.5 Gy gamma radiation and treated with 0 µM LGM2605, respectively (* p < 0.05; ** p < 0.01; *** p < 0.001; **** p < 0.0001).