TNF and Stroke: Finally, it was shown that M2 microglia and A2 astrocytes could be further converted to M1 microglia and A1 astrocytes under an inflammatory microenvironment and stroke-mimicking environment, and TNF-α and IFN-γ increased Bcl-xL expression of microglia, suggesting self-defense mechanism from NO-induced apoptosis [22] (Figure 5, Figure 6 and Figure 7).