IL1B and osteoarthritis: Additionally, in the synovium of osteoarthritis (OA) rats, the knockdown of microtubule affinity-regulating kinase 4 (MARK4) inhibited the interleukin-1β (IL-1β)-stimulated interleukin-6 (IL-6) secretion and activation of the nuclear factor kappa-light-chain-enhancer of activated B cells (NF-KB) pathway in synovial mesenchymal stem cells (SMSCs).