LPAR1 and rheumatoid arthritis: Among LPA receptors, LPA receptor 1 (LPR1) is essential in RAFLS cells, presents in large amounts in the synovial fluids of RA patients 79; berberine is found to block LPR1 and, thereby, suppress the proliferation and redundant generation of inflammatory cytokines IL‐6 and TNF‐α in RAFLS cells through inhibiting activation of Ras/Raf/ERK/p38 axis.77