CCL2 and subarachnoid hemorrhage: STAT3 activation and interaction with p38MAPK occur, while MSC-Exos reduce STAT3 and p38MAPK phosphorylation; it also inhibits the overexpression of the inflammatory mediators cyclooxygenase-2 (COX-2), monocyte chemoattractant protein-1 (MCP-1), and iNOS, leading to neuroprotective effects in subarachnoid hemorrhage (Liu et al. 2021c).