Gene expression profiling data from large cohorts of medulloblastoma tumors qualitatively support our results. In our data set, LGR5 was uniquely over-expressed (120-fold, p =0.01) in the WNT subgroup of tumors compared to normal cerebellum. Over-expression of LGR5 in WNT tumors has been demonstrated in two previously published sets of gene profiling data (a, b)[8, 10]. Our data demonstrate over-expression of GPR64 in the WNT subgroup of tumors (2200-fold, p = 0.04). This aberration was also reported for WNT tumors in the Boston and Toronto series (c, d)[8, 10]. PTGER4 was uniquely over-expressed in the SHH subgroup of tumors in our data set (16-fold, p = 0.02). This pattern of expression was also observed in the Boston and Heidelberg series (e, g)[8, 11]; in the Toronto series (f), the SHH subgroup shows increased PTGER4 expression as compared to Group 3 and Group 4 tumors, but not compared to the WNT subgroup. Blue boxes represent WNT tumors, red boxes represent SHH tumors, yellow boxes represent Group 3 tumors and green boxes represent Group 4 tumors (a, b, c, d, e, f, g). In the Boston series (a, c, e), the grey boxes represent normal cerebellar controls.