Peptide Activating Agent

A peptide for activating Lck, wherein the peptide comprises a Lck activating polypeptide moiety of Formula I or an inverted sequence thereof:

• R/K′-x1-R/K-x2-R/K-x3-x4-x5-x6-R/K″ Formula I
• wherein:
• each R/K is independently an arginine or lysine amino acid residue;
• R/K′ is an arginine or lysine amino acid residue and is present or absent;
• R/K″ is an arginine or lysine amino acid residue and is present or absent;
• x1 to x6 are each independently an amino acid;
• and
• wherein amino acids x3 to x6 are collectively present or absent, and R/K″ is absent when amino acids x3 to x6 are absent.