Signaling adapter that couples activated growth factor receptors to signaling pathway in neurons. Involved in the signal transduction pathways of neurotrophin-activated Trk receptors in cortical neurons (By similarity). Interacts with the Trk receptors in a phosphotyrosine-dependent manner. Once activated, binds to GRB2. Interacts with activated EGF receptors (By similarity). Predominantly expressed in the adult brain. Tyrosine phosphorylated.