Medulloblastoma (MB) is the most common primary malignant pediatric brain tumor. The relationship between stem cell function and invasiveness has not been investigated in MB. We have dissected MB heterogeneity and compared the capacity for self-renewal and invasion. Our laboratory has identified a combination of 3 cell surface markers that can be used to select for cells with a high self renewal capacity or high invasive capacity. CD271 and CD24 cell surface markers were shown to select for cells that exhibited higher self-renewal capacity whereas CD133 selected for higher invasive capacity. The next step was to confirm these findings in vivo. A mouse model was developed and optimized in the laboratory using NOD SCID mice. Initial data has shown mice injected with higher unsorted cell numbers develop tumor symptoms earlier than mice injected with less cells. Additionally, CD271+/133- cells appear to develop tumors at a faster rate than CD271-/CD133- cells.