To observe if ATRA can enhance the bystander effect of HSV-TK/GCV on BIU-87 cells in vitro. And discuss whether the mechanism is associated to the role of improving the expression of Cx26 and the function of GJIC.

• 体外观察ATRA是否有提高HSV-TK/GCV对膀胱癌细胞的旁观者杀伤作用,探讨其作用机理是否与提高Cx26的表达及改善膀胱癌细胞细胞间通讯有关。