Aims: to define cellular heterogeneity and primary resistance mechanism(s) in medulloblastoma (MB) at single cell resolution. Methods: project is based on sequencing primary human MB tumors using single-cell RNA sequencing. Data is analyzed by the novel computational approach Pathway and (PAGODA). Expected result: Since the discovery of cancer stem cells, it has become evident that a small population of cell clones drives development and treatment resistance. Our approach is to use single-cell RNA sequencing to define these cells causing therapy resistance.