PPM1D and neuroblastoma: To assess the cytotoxic effects of different WIP1 inhibitors on cell viability, six neuroblastoma cell lines and the PPM1D-amplified breast cancer cell line MCF-7 were exposed to different concentrations of the WIP1 inhibitors SL-176, SPI-001, CCT007093 or GSK2830371 [47,48,49,50,51].