Astrocytes can support neuronal survival through a range of secreted signals that protect against neurotoxicity, oxidative stress, and apoptotic cascades. To identify proteins contributing to protective intracellular neuronal signalling originating from astrocytes, endogenous PI3K was immunoprecipitated from Ht22 cells exposed to primary astrocyte conditioned media (ACM) or cell free media (CFM), followed by iTRAQ-based quantitative proteomic analysis.