On the other hand, the differences between the lung and breast cancer cell lines could be due to the different expression and localization of the sigma-2 receptors: while the potent sigma-2 receptor-targeting compound FA4 exerts similar effects, the other TSCs, characterized by lower cytotoxic potential, preferentially activate one apoptotic pathway, depending on the different expression/localization of sigma-2 receptors within each cell line. This evidence concerns the gene TMEM97 and breast carcinoma.