NSC-663284 is a potent, selective and irreversible inhibitor of all Cdc25 isoforms, with preference for Cdc25A (IC50 = 29, 95, and 89 nM for Cdc25A, Cdc25B2, and Cdc25C, respectively). Displays > 20- and > 450-fold selectivity over VHR and PTP1B phosphatases respectively. Arrests cells at both G1 and G2/M phase and blocks cdk2 and cdk1 activation. Blocks proliferation of a range of human tumor cell lines (IC50 = 0.2 - 35 μM). MW: 321.76. Purity ≥98%