Phenotypic analysis of early and late passage GRP. Early passage GRP showed small refractive cell bodies and a short stellate or bipolar appearance (A), while a majority of late passage GRP showed comparable morphology with only a small number of cells displaying larger cell bodies and multi branching shapes or cell with flattened morphology, typical of mature astrocytes (F). Quantitative analysis using immunostaining demonstrated that late passage GRP showed astrocyte lineage commitment (increase of GFAP+ and decrease of A2B5+) but still kept immature phenotype (high in Vimentin+ and Nestin+) (B-D, F-G and I). Data are presented in graph as mean ± standard error of the mean (SEM). Asterisk represents significant difference relative in comparison between early and late passage GRP (Student T-test, *P<0.05, **P<0.005). Scale bar = 50μm