MMP1 and rheumatoid arthritis: In addition to promoting collagen synthesis, 10-HDA has been found to inhibit the release of the MMP-1 and MMP-3 from rheumatoid arthritis synovial fibroblasts, possibly through downregulation of the pathway involving JNK/p38 MAP kinases and AP-1 transcription factor (Yang et al., 2010), and of the MMP regulator connective tissue growth factor (Wang et al., 2012).