Feedback inhibitor of fibroblast growth factor mediated Ras- MAPK signaling and ERK activation (PubMed:12807873, PubMed:12958313). Regulates the nuclear ERK signaling pathway by spatially blocking nuclear translocation of activated ERK without inhibiting cytoplasmic phosphorylation of ERK (PubMed:15239952). Mediates JNK activation and may be involved in apoptosis (By similarity). May inhibit FGF-induced FGFR1 tyrosine phosphorylation (By similarity). Might have a role in the early stages of fate specification of GnRH-secreting neurons (By similarity). Inhibits TGFB-induced epithelial-to-mesenchymal transition in lens epithelial cells (By similarity). {ECO:0000250|UniProtKB:Q8JZL1, ECO:0000269|PubMed:12807873, ECO:0000269|PubMed:12958313, ECO:0000269|PubMed:15239952}. This is the function of ENSG00000144730 (IL17RD, interleukin 17 receptor D).