STAT6 and JAK1 are essential for IL-4-mediated suppression of prostaglandin production in human follicular dendritic cells: Opposing roles of phosphorylated and unphosphorylated STAT6

► Inhibition of TGF-β-induced COX-2 protein and mRNA by IL-4. ► Opposing roles of unphosphorylated and phosphorylated STAT6. ► Potential role of regulatory T cells in the germinal center.