Involvement of Tyrosine Phosphatases in Insulin Signaling and Apoptosis in Breast Cancer

摘要

Our preliminary studies demonstrated that increased intracellular calcium activates calpain to induce partial proteolysis and cytoplasmic translocation of PTP1B, a tyrosine phosphatase proposed to regulate signaling by insulin, IGF-1 and other cytokines. Cytoplasmic translocation of PTP1B results in a distinct pattern of protein tyrosine phosphorylation and these events may regulate cell growth or apoptosis by reducing activated growth factor signaling. In this scheme, calcium-mediated apoptosis and growth inhibition may be directed through mobilization of PTP1B.