PLK1 and cancer: We found that high PLK1 expression levels were associated with depressed Treg cell enrichment levels in 16 cancer types (THYM, LUSC, GBM, TGCT, SKCM, PRAD, UCEC, ESCA, UCS, UVM, OV, DLBC, LUAD, STAD, CESC, and KICH) while were associated with enhanced Treg cell activity in 5 cancer types (THCA, KIRC, LIHC, BRCA, and BLCA) (Spearman correlation, FDR<0.1) (Figure 3).