The PI3K complex, composed of PIK3R1 and PIK3CA, co-immunoprecipitates with NTRK3 (TRKC), activated by NTF3 (NT-3) treatment (Yuen and Mobley 1999). Activation of NTRK3 correlates with activating phosphorylation of AKT, the main mediator of PI3K signaling (Tognon et al. 2001, Jin et al. 2008), and is dependent on PI3K activity (Tognon et al. 2001). NTRK3-mediated activation of PI3K signaling depends on SRC activation and the adaptor protein IRS1, but the exact mechanism is not known (Morrison et al. 2002, Lannon et al. 2004, Jin et al. 2008).