MRC1 and rheumatoid arthritis: In RA macrophages, a signaling pathway described to promote the induction of M2 polarization is the adenosine-monophosphate-activated protein kinase (AMPK)/a-acetyl-CoA carboxylase, which promotes the upregulation of macrophage-derived chemokine (MDC), CD206, and IL-10 (Figure 3) (66).