Modulates NTRK1 signaling. Can activate several intracellular signaling pathways, leading to activation of JUN. Promotes apoptosis. Promotes translocation of SORT1 to the cell membrane, and thereby hinders lysosomal degradation of SOTR1 and promotes its interaction with NGFR. Interacts with NGFR. Interacts with NTRK1. Interacts with SORT1. Proteolytic processing gives rise to an intracellular domain that translocates to the nucleus. Detected in lung and testis.