– PTPN6 is an enzyme that belongs to the protein tyrosine phosphatase (PTP) family. PTPs are signaling molecules that regulate a variety of cellular processes including cell growth, differentiation, mitotic cycle, and oncogenic transformation. N-terminal part of PTPN6 contains two tandem Src homolog (SH2) domains, which act as protein phospho-tyrosine binding domains, and mediate the interaction of PTPN6 with its substrates. PTPN6 is expressed primarily in hematopoietic cells, and functions as an important regulator of multiple signaling pathways in hematopoietic cells. It has been shown that PTPN6 interacts with, and dephosphorylate a wide spectrum of phospho-proteins involved in hematopoietic cell signaling.