Peptide P60 has demonstrated potential of inhibiting the immunosuppressive activity of murine and human derived regulatory T-cells (Tregs) and enhances the effector T-cell stimulation in vitro by binding to regulatory T-cells specific forkhead/winged helix transcription factor 3 (FOXP3). Peptide P60 can enter the cells to inhibit FOXP3 nuclear translocation and activity on other transcription factors. In vitro, peptide P60 (100 uM) inhibited murine and human-derived Treg and improved effector T cell stimulation.H-Arg-Asp-Phe-Gln-Ser-Phe-Arg-Lys-Met-Trp-Pro-Phe-Phe-Ala-Met-OH or H-RDFQSFRKMWPFFAM-OH