Coordinated overexpression of FOXM1 and PLK1 is associated with poor prognosis in HCC. Correlation between FOXM1 and PLK1 expression in HCC in the (A) TCGA and (B) ICGC JP cohorts based on Pearson's correlation analysis. Kaplan-Meier survival curve estimates of overall survival in the (C) TCGA (n=323) and (D) ICGC JP (n=201) cohorts. The patients were divided into two subgroups: High FOXM1+PLK1 and low FOXM1+PLK1. (E) Kaplan-Meier survival curve estimates of disease-free survival in the TCGA cohort (n=276). (F) Transforming growth factor-β response score of HCC in the TCGA cohort, stratified by the co-expression status of FOXM1 and PLK1. (G) Tumor-infiltrating Tregs in HCC in the TCGA cohort, stratified based on the co-expression status of FOXM1 and PLK1. FOXM1, forkhead box protein M1; PLK1, polo-like kinase 1; HR, hazard ratio; TCGA, The Cancer Genome Atlas; ICGC JP, International Cancer Genome Consortium Japan; HCC, hepatocellular carcinoma; NA, not available; Tregs, regulatory T cells.