ENO2 and concussion: Biomarkers that have been previously studied in the context of mTBI include glial fibrillary acidic protein (GFAP), S100β, neuron-specific enolase (NSE), ubiquitin C-terminal hydrolase L1 (UCH-L1), tau, alpha-II spectrin, and neurofilament light (Nf-L) [14,15].