Phosphatase of regenerating liver-3 (PRL-3) has been suggested as a potential target for anticancer drugs based on its involvement in tumor metastasis. However, little is known about a small-molecule inhibitor against PRL-3. In this study, we report that curcumin, the component of the spice turmeric, shows its antitumor effect by selectively down-regulating the expression of PRL-3 but not its family members PRL-1 and -2 in a p53-independent way. Curcumin inhibited the phosphorylation of Src and stat3 partly through PRL-3 down-regulation.