PTGS2 and central nervous system cancer: Wei et al. (2014) tested the effect of Pb at concentrations from 25 μM to 100 μM on COX-2 induction in different cell types: rat C6 glioma cells, mouse BV2 microglia, in primary cultures of cortex neurons, in neural stem cells (NSCs) and RBE4 cells (brain endothelium) [26].