Flow cytometric analysis revealed that cinobufagin substantially arrested cell cycle at G2 and S phases in U87MG-Vehicle, U87MG-EGFRvIII, and U87MG-EGFR cells, except for U87MG-PTEN cells, suggesting that the cell cycle arrest contributes to cinobufagin’s antiproliferative effect in GBM cells (Supplementary Figure S1). This evidence concerns the gene PTEN and glioblastoma.