Figure 8.

Schematic representation of the signaling pathways activated by SDF-1α in primary astrocytes. SDF-1α binding to CXCR4 elicits intracellular signaling including the Erk1/2 MAPK cascade, which initiates activation of TNF-α transcription. TNF-α protein is then synthesized and secreted to the extracellular space (or medium), where it binds to its receptors. TNF-α engagement with its receptors initiates signals leading to cell death and activation of NF-κB and Erk1/2 MAPK. Activated NF-κB and Erk1/2 MAPK in turn translocate to the nucleus and activate IL-1 and RANTES expression.