A potent, selective, reversible Cdc25 dual specificity phosphatase inhibitor with Ki of 32/96/40 nM for Cdc25A/B/C, respectively; displays 125- and 180-fold selectivity over VH1-related dual-specificity phosphatase and PTP1B; shows significant growth inhibition in cancer cells and blocks G(2)/M phase transition; also inhibits cellular MKP-1 and MKP-3 with IC50 of 13 uM.