The expression of S100A8 in microglial cell induces apoptosis of neuronal cells in hypoxic condition. (A,B) SH-SY5Y cells incubated without or with S100A8 KD BV-2 cells for 48 h in hypoxic condition. Cleaved caspase-3 immunofluorescence images and were detected and quantitative analysis of the number of cleaved-caspase3-positive cells are shown in lower panel. (C,D) Representative Annexin-V/PI images were detected by flow cytometry. Quantitative analysis of the apoptotic rate of SH-SY5Y cells are shown in lower panel. (E,F) Primary neuron-glial mixed cells were transfected with S100A8 shRNA vector for 24 h followed by 48 h in hypoxic condition. Cells were harvested, and the expression protein levels of S100A8 and cleaved caspase-3 were analyzed by Western blotting. Data from three independent experiments are presented as the means ± S.D. Values of *** p < 0.001 versus control; # p < 0.05, ### p < 0.001 versus hypoxia-exposed sample were considered as statistically significant.