Cyclopentanone, 2,5-bis(2-thienylmethylene)-

A cell-permeable thienylidene cyclopentanone compound that inhibits the PPM ser/thr phosphatase member PPM1D/PP2Cδ/WIP1 (IC₅₀ = 8.4 μM), while exhibiting little activity against PPM1A even at concentrations as high as 100 μM. Selectively inhibits the growth of high PPM1D-expressing tumor cells (SF₅₀ = 0.13, 0.17 & 0.48 μM for MCF-3B, KPL-1, & MCF-7, respectively, in colony formation assays), but not low PPM1D-expressing tumor cells (SF₅₀ = 34 & >50 μM for 239T & HeLa, respectively). Inhibition of p38 MAP kinase activity by SB203580 (Cat. Nos. 559389, 559395, & 559398) is shown to fully prevent PPM1D inhibitor-induced growth arrest of MCF-7 cells.