Specificity:Recognizes phosphorylated serine both as free amino acid or when coupled to carriers such as BSA or KLH. Does not crossreact with non-phosphorylated serine, phosphothreonine, phosphotyrosine, AMP or ATP. Certain proteins known to contain phosphorylated serine may not be recognized by this antibody because of steric hindrance of the recognition site. Species Crossreactivity: rat