A method for identifying modulators of Interleukin 24 (IL-24) mediated apoptosis is disclosed. For IL-24 apoptosis to be effective, the cells should express Sigma 1 Receptor (S1R). Additionally apoptosis modulators can be identified by exposing biological cells to test compounds and monitoring for signs of endoplasmic reticulum (ER) stress protein expression calcium mobilization or reactive oxygen species (ROS) production.