TCS 401 is a selective inhibitor of protein-tyrosine phosphatase 1B (PTP1B), which plays a key role in the negative regulation of the insulin signaling pathway, contributing to insulin resistance. It exhibited Ki values of 290 nM for PTP1B, with greater than 100-fold or more selectivity compared to other phosphatases. Inhibition of PTP1B by TCS 401 has been shown to sensitize the insulin signaling pathway and increase dopamine release in response to insulin. TCS-401 has also been shown to promote endothelial cell motility and to induce differentiation of retinal pigment epithelial cells toward improved contractility and motility.
