translation.en: And the two pieces are then linked by something that can only be cut if you have the right molecular scissors -- for example, the kind of protease enzymes that tumors make.
translation.zh: 这两个部分又通过其它部分相连， 只有用合适的分子剪刀， 才能剪掉这个部分。 譬如说，这种肿瘤制造的 蛋白酶