Neman et al. demonstrated that metastatic breast cancer cells were juxtaposed to reactive astrocytes expressing glial fibrillary acidic protein (GFAP) both in the peritumoral brain and tumor regions, which showed a hypertrophic morphology comparable to astrocytes in glial scars forming in response to traumatic brain injury (Herrmann et al., 2008). Here, GFAP is linked to breast carcinoma.