CTLA4 and cervical squamous intraepithelial neoplasia: In comparison to CIN-low tumors, CIN-high murine tumors display a heavily immunosuppressive TME characterized by the presence of dysfunctional CD8+ T cells expressing exhaustion markers such as TOX, PD-1, TIM-3, LAG-3 and CTLA-4; pro-tumor M2-like macrophages and granulocytic MDSCs.