Interleukin-17 receptor D (IL-17D) also known as Interleukin-17 receptor-like protein, is a member of the interleukine-17 receptor family. IL-17RD functions as a feedback inhibitor of fibroblast growth factor-mediated Ras-MAPK signaling and ERK activation. It may inhibit FGF-induced FGFR1 tyrosine phosphorylation, regulate the nuclear ERK signaling pathway by spatially blocking nuclear translocation of activated ERK By similarity, and mediate JNK activation and may be involved in apoptosis. IL-17RD is found expressed in the neopallial cortex, rhombic lip, and dorsal regions of the myelencephalon and the frontal nasal process. IL-17RD is also expressed in the commissural plate and septal area of the forebrain and the hippocampus, lens, and optic cup. In the oral region, IL-17RD is expressed in the tongue and the mesenchyme of the first branchial arch. It is also expressed in the developing inner ear. IL-17RD interacts with both IL-17R-Myc and IL-17RB-Myc. Both the intracellular and extracellular domains of IL-17RD interact with IL-17R. IL-17R forms a heteromeric complex with IL-17RD. Experiment results indicate that IL-17RD can affect IL-17R localization, suggesting that these two molecules are colocalized and associate with each other within cells. The fact that IL-17RD Delta ICD is unable to mediate IL-17 signaling but functions as a dominant-negative form indicates that the intracellular domain of IL-17RD is pivotal. Also, IL-17RD interacts with the IL-17R downstream molecule TRAF6. It has been proposed that the IL-17RD intracellular domain interacts with IL-17R and TRAF6 to deliver the downstream signal.