This kit offers a set of seven different MAbs specific for tyrosine phosphorylation sites. Phosphorylation patterns in a given cell extract may differ when probed with different antibodies due to sequence specificity. Recognition therefore depends on two criteria: Phosphorylation and surrounding aa motif. If one of the two criteria is not fulfilled, the antibody will not detect the phosphorylation site. Specificity has been determined by epitope mapping using degenerated phosphopeptide libraries.