Proinflammatory signaling initiated by leukotriene LTB4 through its BLT1 and BLT2 receptors (encoded by LTB4R and LTB4R2 genes) is associated with various diseases, such as asthma, rheumatoid arthritis, atherosclerosis, abdominal aortic aneurysm, multiple sclerosis, and cancer. Here, LTB4R is linked to rheumatoid arthritis.