Lambda Protein Phosphatase (Lambda PP) is an Mn2+-dependent protein phosphatase that treats phosphorylated serine Threonine and tyrosine residues have dephosphate activity. It is a product containing 221 amino acid residues encoded in the open reading box ORF221 on the lambda phage. Lambda PP can be used for dephosphorylation of proteins, which in turn can be used to study the relationship between protein phosphorylation and its activity and structure, and to verify the specificity of antibodies at protein phosphorylation sites.