CD44 and breast cancer: Multiplex SERS nanotags successfully detected cancer biomarkers EGFR (cell surface receptor for EGFR family members), CD44 (cell surface adhesion molecule and receptor for the glycosaminoglycan, hyaluronan), and TGFβRII (receptor for the anti-proliferative TGFb ligand) in an MDA-MB-231 breast cancer xenograft mouse model [118].