OGD-conditioned culture media caused increased neuronal death in cortical neuronal cultures. Primary cortical cultures at DIV 12 were exposed to OGD and conditioned media (CM) were collected, centrifuged and concentrated as described in the methods. A) Western blot analysis of CM from OGD-exposed WT primary cortical cultures showed OGD time-dependent increase of NP1 protein levels. B) This CM of OGD exposed WT cultures (WT-OGD CM) was added to a subset of control cortical cultures for 24 h (Control + WT-OGD CM). In addition, another subgroup of cells was also exposed to 6 h of OGD (WT-OGD CM + OGD). Data shown are mean ± SEM (n = 8 in each group) and repeated two times, **p < 0.01 vs. normoxia controls; +p < 0.01 vs. OGD only and Control + WT-OGD CM group.