PROBLEM TO BE SOLVED: To provide cell death inducers having cell death inductive action and/or cytostatic action, against cancer cells, to provide pharmaceutical compositions containing the cell death inducers, and to provide screening methods of the cell death inducers and/or cytostatic agents.SOLUTION: The present invention provides a cell death inducer or a cytostatic agent of cancer cells containing as active ingredients a drug inhibiting π(GST-π) which is one isozyme of glutathione-S-transferase, and a drug inhibiting a homeostasis maintenance-associated protein which exhibits synthetic lethality when inhibited with GST-π； and a pharmaceutical composition containing the cell death inducer； wherein the homeostasis maintenance-associated protein which exhibits synthetic lethality when inhibited with GST-π is a protein selected from a cell cycle regulating protein, an anti-apoptosis associated protein, and a PI3K signal transduction pathway associated protein.SELECTED DRAWING: Figure 12【課題】がん細胞に対して、細胞死誘導作用及び／又は細胞増殖抑制作用を有する細胞死誘導剤、該細胞死誘導剤を含む医薬組成物、及び細胞死誘導剤及び／又は細胞増殖抑制剤をスクリーニングする方法の提供。【解決手段】グルタチオン－Ｓ－トランスフェラーゼのアイソザイムの一つであるπ（ＧＳＴ－π）を抑制する薬物と、ＧＳＴ－πとともに抑制されると合成致死性を示す恒常性維持関連蛋白質を抑制する薬物とを有効成分として含む、がん細胞の細胞死誘導剤、及び該細胞死誘導剤を含む医薬組成物。ＧＳＴ－πとともに抑制されると合成致死性を示す恒常性維持関連蛋白質が細胞周期調節蛋白質、抗アポトーシス関連蛋白質及びＰＩ３Ｋシグナル伝達経路関連蛋白質から選ばれる蛋白質である、がん細胞の細胞死誘導剤又はがん細胞の細胞増殖抑制【選択図】図１２
