GFAP and glioblastoma: For example, Lynch et al. established an immunomagnetic enrichment method targeting MCAM (melanoma cell adhesion molecule) and MCSP (melanoma-associated chondroitin sulfate proteoglycan), followed by the use of GLAST (glutamate aspartate transporter) and GFAP (glial fibrillary acidic protein) to differentiate CTCs from lymphocytes, thereby improving the identification of GBM-derived CTCs [17].