Plays a role in fibroblast growth factor-mediated signaling cascades that lead to the activation of MAP kinases (PubMed:16872596, PubMed:20421966). Promotes neurite outgrowth via FGFR1-mediated activation of downstream MAP kinases. Promotes an increase both in neurite number and in neurite length (PubMed:20421966). May play a role in cell-cell adhesion and cell guidance via its interaction with ADGRL1/LPHN1 and ADGRL3 (PubMed:22405201). Interacts with FGFR1 (PubMed:16872596). Interacts (via extracellular domain) with ADGRL1/LPHN1 and ADGRL3 (via olfactomedin-like domain) (PubMed:22405201). In addition to its location at the cell membrane, colocalizes with FGFR1 in punctate perinuclear cytoplasmic vesicles (PubMed:16872596, PubMed:20421966). Detected along neurites and at contacts between neurite termini and other cells (PubMed:20421966). Proteolytic cleavage gives rise to a shedded ectodomain (PubMed:21673655). Detected in brain (at protein level). Detected at comparable levels in embryonic brain and in brain from ten day old animals (at protein level) (PubMed:16872596). Detected in neuroectoderm at 7.5 dpc. Detected in midbrain between 8.5 and 9 dpc (PubMed:18448090). Detected at 9.5 dpc in embryonic midbrain adjacent to the boundary between midbrain and forebrain (PubMed:16872596). At 10.5 dpc, expression is also detected in the eye, throughout the brain, the dorsal root ganglia and trigeminal ganglia, and in cells adjacent to the urogenital ridge in the torso (PubMed:16872596, PubMed:18448090). At 11 dpc, expression in midbrain is tightly restricted to the boundary between midbrain and hindbrain (PubMed:16872596). Up-regulated by FGF2. Phosphorylated in response to FGFR1 signaling, but is not a direct substrate of FGFR1 or SRC. A mutant where the Tyr phosphorylation sites have been replaced by Phe displays constitutive FGFR1-dependent activation of downstream MAP kinases. N-glycosylated. Proteolytic cleavage in the juxtamembrane region gives rise to a soluble ectodomain. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus. Extended N-terminus.