CX3CL1 and brain ischemia: Although it has been shown that CX3CL1 contributes to the maintenance of microglia in a quiescent state (see [49], [50]) others reported that soluble CX3CL1 increases in cerebral ischemia [51], in response to apoptosis [52] and glutamate stimulation [22];it is neuroprotective in cultured rat hippocampal neurons [53] indicating that CX3CL1’s actions may differ depending upon different stimuli.