SPP1 and brain ischemia: It is present in nearly all neurons, glial cells, and immune cells.59 Numerous studies have found that OPN has neuroprotective effects and can promote the repair of conditions such as stroke, cerebral ischemia, and Traumatic Brain Injury (TBI).60 Robert Meller et al. discovered in a stroke model that OPN promotes the phosphorylation of Akt, achieving neuroprotection through the PI3K/Akt pathway.25 The neuroprotective effect induced by OPN was blocked by the PI3K inhibitor LY294002.