Modulates NTRK1 signaling. Can activate several intracellular signaling pathways, leading to activation of JUN. Promotes translocation of SORT1 to the cell membrane, and thereby hinders lysosomal degradation of SOTR1 and promotes its interaction with NGFR (By similarity). Both isoform 1 and isoform 2 promote apoptosis. Interacts with NTRK1 (By similarity). Isoform 1 and isoform 2 interact with NGFR. Interacts with SORT1. Proteolytic processing gives rise to an intracellular domain that translocates to the nucleus. Detected in embryo, including embryonic brain. Detected at very low levels in adult testis, spleen, thymus and lung. Highly expressed in embryo. Expressed at very low levels in adult. Isoform 1 is N-glycosylated. Isoform 2 is not N-glycosylated.