CST3 and Stroke: Among the upregulated proteins at 24 h and 4 days after tMCAO, we found that cystatin C (CysC, CST3), a protease inhibitor known to exert protective effects against ischemic brain injury and neurodegeneration [29, 30] was significantly (p = 0.032) upregulated (Fig. 2A and B, in red) by threefold in the stroke synaptosome preparations.