To explore the potential mechanism by which an AngII signaling blockage enhances tumor responses to checkpoint immunotherapy, we first performed multicolor flow cytometry analysis (FACS) to detect the proportions of effector T cells ( Teffs ) and regulatory T cells ( Tregs ) in 4T1 breast tumors from BALB/c mice treated with Ang II-receptor blockers. This evidence concerns the gene AGT and breast neoplasm.