In patients with RA remission, the level of phosphatidyl acid (PA(28:0)) in synovial fluid significantly increased, which stabilized SCAP-SREBP complex on the endoplasmic reticulum by binding to Insig protein, and inhibited the expression of HMGCR, a key enzyme in cholesterol synthesis (76, 78, 79). Here, SCAP is linked to rheumatoid arthritis.