Injection of recombinant HMGB1 (Figure 4(a)), a known endogenous TLR4 ligand released during focal cerebral ischemia, results in a trend towards an almost 2-fold increase in expression of TLR4, when injected into normal rat cortex; Figure 4(b) ((A) and (C)). Here, HMGB1 is linked to brain ischemia.