The mechanism of PLK1 inhibiting tumor immunity and the viability of the PLK1 inhibition and immunotherapy combination in cancer treatment. (a) PLK1 inhibits tumor immunity via regulating the cell cycle and p53 pathways. (b) The cancers with higher PLK1 expression levels show a higher prevalence of TP53 mutations compared to the cancers with lower PLK1 expression levels in 12 cancer types (Fisher's exact test, FDR<0.05). OR: odds ratio. (c) The PLK1 inhibition and immunotherapy combination is viable in promoting the antitumor efficacy.