At this point, it is difficult to infer thecellular network through which this TLR4-MyD88 signaling is mediated.Functional TLR4 and MyD88 signaling is present in microglia,astrocytes, and neurons and plays a prominent role in the initiationof pain states at the level of the first- and second-order sensoryneurons.43, –45 Importantly, most migraine research targets thebiology of sensory neurons, but given the potential role ofneuro-inflammatory signaling, non-neuronal cell types such asastrocytes and microglia must also be examined. Here, TLR4 is linked to migraine disorder.