MAPK1 and rheumatoid arthritis: JUN is a major component of AP-1, which determines the expression of many pro-inflammatory proteins in RA.[36] MAPK protein kinase is involved in the signaling process from the cell membrane to nucleus and regulates cell growth, differentiation, stress, inflammation, and other cell pathological and physiological processes.[37] Therefore, melittin may inhibit the activation of JUN and ERK1/2 (MAPK3, MAPK1) pathways, thereby effectively blocking inflammatory responses, which was confirmed in this study.