CXCR4 and Alzheimer disease: In the CNS, extracellular HMGB1 binds to a number of receptors, including toll-like receptor (TLR) 4 receptors, receptor for advanced glycation end-products (RAGE) and C-X-C chemokine receptor type 4 (CXCR4) and binding to these receptors leads to inflammation, which may be an important mechanism of neurological disorders such as Alzheimer’s diseases, Parkinson’s disease and stroke [6].