Peptide P60 acts as a FOXP3 inhibitor. This compound can penetrate cells to hinder FOXP3's nuclear translocation and diminish its ability to suppress transcription factors NF-κB and NFAT. Peptide P60 also suppresses the immunosuppressive activity of regulatory T cells (Treg) derived from mice and humans, while enhancing effector T cell stimulation in vitro. Moreover, Peptide P60 can induce a lymphoproliferative autoimmune syndrome, displaying pathological characteristics similar to those observed in scurfy mice lacking functional Foxp3. Additionally, Peptide P60 has the potential to boost the immunogenicity of cancer and viral vaccines.