CERNA1 and glioblastoma: Secondly, to further narrow down the number of prognostic PCGs or lncRNAs, we analyzed the above 707 survival related genes by random survival forest algorithm and got six PCGs (EIF2AK3, EPRS, GALE, GUCY2C, MTHFD2, RNF212) and six lncRNAs (LINC00618, LINC02015, AC068888.1, CERNA1, CTD-2140B24.6, ZMIZ1-AS1) significantly associated to OS of GBM patients according to the permutation important score in every step: Discard 1/4 less important PCGs and lncRNAs at each step based on estimating the important score for each PCG or lncRNA using the out-bag samples by pemutation testing (Fig. 1b–d).