TNF and rheumatoid arthritis: Furthermore, sensory nerve fibers in human labrum and synovium have been found to be immunoreactive with protein gene product 9.5, calcitonin gene-related peptide (CGRP) and tumor necrosis factor (TNF)-α in patients with hip pain or rheumatoid arthritis (RA) [6], suggesting the possible involvement and regulation of sensory nerves in the pathogenesis of hip pain.