Stat3 Inhibitor V, Stattic is a small molecule shown to selectively inhibit the activation of the Stat3 transcription factor by blocking phosphorylation and dimerization events. Stattic has been used as a tool for probing the upstream activation of this factor, significantly expressed in many cancer cell lines, and interruption of this pathway in breast cancer cell lines lead to an increased apoptotic rate in these cells. Stat3 Inhibitor V, Stattic is an inhibitor of Stat3.