CDC25 Phosphatase Inhibitor II, NSC 663284

CDC25 Phosphatase Inhibitor II (NSC 663284) is a cell-permeable, 7-substituted quinolinedione compound that is a potent, irreversible, mixed competitive inhibitor of the CDC25 phosphatase family (K_i = 29 nM, 95 nM and 89 nM for CDC25A, CDC25B and CDC25C, respectively, IC₅₀ = 210 nM for CDC25B). CDC25 dual-specificity phosphatases coordinate cell cycle progression and cellular signaling. CDC25 Phosphatase Inhibitor II has been shown to arrest synchronized cells at both G₁ and G₂/M phases, and block dephosphorylation and activation of Cdk1 and Cdk2. This product was 20-fold more selective against CDC25B as compared to VHR phosphatase and 450-fold more selective as compared to PTP1B phosphatase, and also blocked cellular Erk dephosphorylation. Recent research shows that CDC25 Phosphatase Inhibitor II induces reactive oxygen species in mammalian cells, but does not inhibit MKP-1 and MKP-3.