PLK4 and neoplasm: Although the infiltration of immune cells such as CD8+ T cells and macrophage M1 increased with the increase of PLK4 expression level, the expression level of PLK4 was also positively correlated with the tumor proliferation-promoting cytokines in the immunosuppressive microenvironment from the perspective of immunosuppressive cytokines; so, these cytokines may be involved in the formation of tumor immunosuppressive microenvironment.