IL1B and rheumatoid arthritis: Recently, CB2 was shown to be upregulated by stimulation with IL‐1β, TNF‐α or lipopolysaccharide in synovial fibroblasts of patients with rheumatoid arthritis, and the selective CB2 agonist HU‐308 inhibited IL‐1β‐induced production of IL‐6 and IL‐1β‐induced activation of Erk 1/2 and p38 MAPK (Gui et al.