In addition, another BH3 mimetic compound S63845 has been developed, which specifically binds with high affinity to the BH3-binding groove of Mcl-1 (25), since 10% of cancers highly express Mcl-1 that not only mediates malignant cell survival and expansion in several primary tumors but also contributes to tumor resistance to various chemotherapeutic agents (28, 32). This evidence concerns the gene MCL1 and cancer.