It's a gene that allows you to deliver a drug that's not active but the gene causes that active - that inactive drug to be converted into an active form that kills the cell.

这一方法利用该基因激活,另一种已经导入细胞的非活性药物,来杀死肿瘤细胞

耶鲁公开课 - 生物医学工程探索课程节选