Cellular biological activities are tightly controlled by intracellular signaling processes initiated by extracellular signals. Protein tyrosine phosphatases, which remove phosphate groups from phosphorylated signaling molecules, play equally important tyrosine roles as protein tyrosine kinases in signal transduction. SHP-2, a cytoplasmic SH2 domain containing protein tyrosine phosphatase, is involved in the signaling pathways of a variety of growth factors and cytokines. Recent studies have clearly demonstrated that this phosphatase plays an important role in transducing signal relay from the cell surface to the nucleus, and is a critical intracellular regulator in mediating cell proliferation and differentiation.