The CSC compartment represents the subpopulation of tumor cells with clonogenic potential and the ability to initiate new tumors. Besides self renewal, one of their main features is their ability to differentiate into the variety of cells within the tumor. The question remains whether this potential resides within the single CSC or whether many different CSCs are necessary to generate a heterogeneous population of tumor cells. There is an increasing amount of evidence showing that a single CSC indeed has the potential to reconstitute the complete tumor phenotype. This is likely to be a general phenomenon and it has been demonstrated in many tumors so far. Here we show that single GBM CSCs have multilineage potential, although not exclusively. Furthermore, our results show that CSCs originating from same tumor are not necessarily uniform in respect to their differentiation potential.