Protein tyrosine phosphatases remove phosphates from the phosphotyrosine residues of target proteins and reverse the action of various protein tyrosine kinases. This essential interplay between the opposing actions of protein tyrosine phosphatases and protein tyrosine kinases forms the basis of signaling networks that underlie the cellular workings of human physiology. Initially passed-off as housekeeping genes; these proteins were only acknowledged to maintain a steady background of phosphotyrosine levels in the cell. However, recent progress in studying their role in embryonic development...