Proposed mechanism of taurine protection against ER stress induced by oxidative stress in PC12 cells. There are four stages to the process. 1, ROS (H2O2) induces ER stress; 2, this leads to up-regulation of the ER stress marker GRP78 and CHOP/GADD153. 3, CHOP induces apoptosis and up-regulation of BH3-only proapoptotic protein Bim and inhibits the expression of Bcl-2. 4, Bim induces cell apoptosis. Taurine exerts its protection against oxidative stress induced by ROS (H2O2). Taurine suppresses ER stress induced by oxidative stress through down-regulating the expression of GRP78 and CHOP. Furthermore, taurine protects PC12 cells by up-regulation of Bcl-2 and down-regulation of Bim.