NANOG and central nervous system cancer: We demonstrate that RNAi against SPP1 reduced the number of spheres formed by LN18 and rat C6 glioma cells, and down-regulated OCT4 and NANOG. Rat C6 glioma cells with stable knockdown of Spp1 had reduced levels of Oct3/4 and Nanog expression in sphere cultures along with the reduced sphere numbers (Figure 6).