MMP9 and migraine disorder: Correlation between sICAM-1 and MMP-9 is similarly expressed in healthy individuals and in migraine patients without aura (rS = −0.40 and rS = −0.37), but these patients have three other inverse correlations: sICAM-1 correlates with PAI-1 (rS = −0.72), with TGF-α (rS = −0.45), and with MCP-1 (rS = −0.39).