Plays a role in fibroblast growth factor-mediated signaling cascades that lead to the activation of MAP kinases. Promotes neurite outgrowth via FGFR1-mediated activation of downstream MAP kinases. Promotes an increase both in neurite number and in neurite length. May play a role in cell-cell adhesion and cell guidance via its interaction with ADGRL1/LPHN1 and ADGRL3. Interacts with FGFR1. Interacts (via extracellular domain) with ADGRL1/LPHN1 and ADGRL3 (via olfactomedin-like domain). In addition to its location at the cell membrane, colocalizes with FGFR1 in punctate perinuclear cytoplasmic vesicles. Detected along neurites and at contacts between neurite termini and other cells. Proteolytic cleavage gives rise to a shedded ectodomain. Expressed in kidney and brain. N-glycosylated. 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 A mutant where the Tyr phosphorylation sites have been replaced by Phe displays constitutive FGFR1-dependent activation of downstream MAP kinases. Proteolytic cleavage in the juxtamembrane region gives rise to a soluble ectodomain.