To further investigate the potential of targeting MDM2 in vitro, we tested RG7388, a second-generation inhibitor of MDM2 in ten DIPG patient-derived cell lines that were characterized genetic mutations common to DIPGs, including H3K27M, TP53, and PPM1D mutations (Additional file 1: Fig. S1). The gene discussed is PPM1D; the disease is diffuse intrinsic pontine glioma.