(A) Estimated frequency of tumor-initiating cells determined from in vitro limiting dilution assays for GNS 179 cells expressing the GFP-tagged fusion proteins. N=3 trials. (B) Cell proliferation assay comparing the growth of parental GNS 179 cells, GNS 179 GFP, GFP-Kif2A, GFP-MCAK, and GFP-MCAK Hypir expressing cells. The cell lines expressing the GFP-tagged fusion proteins were sorted into populations of low and high GFP expressing cells. Growth was then monitored every other day for 11 days total with an alamarBlue® assay. Three independent replicates were performed and error bars represent ±SD. (C) A table of the population doubling time during the exponential growth phase (days 3–9) of the various cell lines. (D) The astrocyte differentiation frequency of GNS 179 GFP, GFP-Kif2A, GFP-MCAK, and GFP-MCAK Hypir expressing cells as measured by the mean percentage of cells expressing the astrocyte marker GFAP after growth in the presence of 10ng/ml BMP-4 for 8 days. N≥300 total GFP+ cells scored from three independent experiments. Errors bars represent ±SD and *p<0.05, Student’s T-test compared with control GFP-Kif2A expressing cells.