TRAPPC9, also named NIK- and IKBKB-binding protein (NIBP), is involved in the NF-kappaB signaling pathway and directly interacts with IKK-beta and MAP3K14. TRAPPC9 functions as an activator of NF-kappa-B via increased phosphorylation of the IKK complex. TARPPC9 may also function in neuronal cells differentiation and defects in TRAPPC9 are the cause of mental retardation autosomal recessive type 13 (MRT13), which is characterized by significantly below average general intellectual functioning associated with impairments in adaptative behavior. TARPPC9 is a component of the multisubunit TRAPP (transport protein particle) complex and it may play a role in vesicular transport from endoplasmic reticulum to Golgi.