BMI1 IP followed by western blotting confirmed that PRP6 is bound to BMI1 in GBM cell lines as well as GIC (Supplementary Figure S4A, B), although it seemed to be not concordantly modulated by BMI1 expression levels in GIC (Figure 1D), possibly because of the difference in sensitivity between IP-MS and IP-western blot or because of the different silencing method used in GIC. The gene discussed is PRPF6; the disease is glioblastoma.