IGKV1D-22 and arthritic joint disease: Upregulated αvβ3 and α5β1, in turn, further activate proinflammatory cytokine production, which mediates smooth muscle cell and endothelial cell proliferation and migration and platelet activation.541–543 Furthermore, α9 is reported to be overexpressed both in animal models of arthritis and in RA patients, and increased α9 expression precedes the onset of arthritic symptoms.