Muller et al identified CTCs in 29 of 141 (20.6%) of GBM patients using glial fibrillary acidic protein-directed antibodies.75 Krol et al isolated GBM CTCs from peripheral blood samples of 7 of 13 (53.8%) patients using immunostaining and exome-sequencing techniques, but they did neither find any association between the presence of CTCs and MRI volume nor any of those patients developed extracranial metastasis.76 Here, GFAP is linked to glioblastoma.