PRDM9 and hepatocellular carcinoma: Figure 1A shows a flowchart with the following steps for constructing a screening system to identify novel prognostic markers in HCC: 1) Collect RNA-seq data (Normal/Cancer) TCGA portal; 2) Analyze expression levels using an in silico panel including histone methyltransferases/demethylases; 3) Test the possibility of a prognostic marker by Kaplan-Meier plot and log-rank test (P < 0.05); and 4) Analyze the function/pathway.