DLDVPIPGRFDRRVpSVAAE (H-Asp-Leu-Asp-Val-Pro-Ile-Pro-Gly-Arg-Phe-Asp-Arg-Arg-Val-Ser (PO₃H₂) -Val-Ala-Ala-Glu-OH) is an excellent peptide substrate for calcineurin (Protein Phosphatase 2B, PP2B) .