Human neural progenitor cells were isolated under selective culture conditions from the developing human brain and directed through lineage differentiation to GFAP + (glial fibrillary acid protein) astrocytes. Following 3 weeks in astrocyte selective medium, cells were fixed and stained with antibodies to intermediate filament proteins that characterize the cells as either astrocytes (GFAP in orange) or neural progenitor cells (nestin in green). Nuclei are stained with DAPI in blue. Microscopic examination over the course of differentiation showed loss of progenitor cells (nestin down regulation) as cell population increasingly became astrocytes (GFAP up regulation). Photomicrograph was taken on Axiovert 200M Zeiss inverted microscope at 200 x magnification.