The GFP-positive cells from tumors transduced with LCMV-GP or VSV-G pseudotyped lentiviral vectors were sorted and cultured in neural basal medium supplemented with EGF and bFGF. Transduced tumor cells from both vectors were able to form spheroids ( Figure 5B,E) . Spheroids expressed the stem cell markers nestin and SOX2 ( Figure 5C,D,F,G) . Sorted cells were also plated under serum conditions. The cells continued to show significant expression of the stem cell markers nestin and SOX2, but also of the differentiation markers GFAP and b-tubulinIII ( Figure 5H-O) .