An engineered protein modeled after components of the growth factor progranulin can reduce the symptoms of rheumatoid arthritis in mice (Tang W et al. Science. doi:10.1126/science.1199214 [ published online ahead of print March 10, 2011]).
Despite progranulin's critical role in a variety of diseases, researchers have been unable to identify its binding receptors. When scientists in the United States and China used genetic screening techniques, they discovered that progranulin binds to the receptor for the inflammatory protein tumor necrosis factor (TNF). They also observed that progranulin-deficient mice were susceptible to arthritis.
Hampton T. Arthritis Target. JAMA. 2011;305(17):1756. doi:10.1001/jama.2011.545