Endogenous neural stem cells reside in the mammalian brain during development and within special niche microenvironments during adulthood. We discovered that endothelial progenitor cell-secreted factors promote the self-renewal of adult mouse NSCs in vivo and identified this protein as ECF-L. We also analyzed molecular signalling networks caused by ECF-L in neural stem cells using global gene expression analysis. Neural stem cells were isolated and expanded from adult mouse brain. Neural stem cells were cultured in the presence or absence of ECF-L in the MHM medium. After the designed period of ECF-L treatment, cells were harvested and RNA was extacted, followed by DNA microarray analysis.