BH3 mimetics are small-molecule inhibitors of B-cell lymphoma-2 (Bcl-2) and Bcl-xL, which disrupt the heterodimerisation of antiand pro-apoptotic Bcl-2 family members sensitising cells to apoptotic death. These compounds have been developed as anticancer agents to counteract increased levels of Bcl-2 proteins often present in cancer cells. Application of a chemotherapeutic drug supported with a BH3 mimetic has the potential to overcome drug resistance in cancers overexpressing anti-apoptotic Bcl-2 proteins and thus increase the success rate of the treatment. We have previously shown that the BH3 mimetics, BH3I-2′ and HA14-1, induce Ca 2+ release from intracellular stores followed by a sustained elevation of the cytosolic Ca 2+ concentration.