This gene can conert a less toxic drug, 5-fluorocytosine (5-FC), to 5-FU inside the stem cells, and the chemotherapy can then seep out into the tumor, producing a lethal by-stander effect.

• 该基因可在干细胞中将毒性小的5-氟胞嘧啶(5-FC)转变为5-FU，该化疗药物由干细胞进入肿瘤细胞，产生致死性的旁观者效应。