Therefore, to establish the importance of these BCL-2 family of anti-apoptotic proteins in SCLC, we systematically evaluated the effects of inhibitors of BCL-2 family anti-apoptotic proteins, i.e., A1155463 (a selective BCL-XL inhibitor), venetoclax (a selective BCL-2 inhibitor), S63845 (a selective MCL-1 inhibitor) and navitoclax (a BCL-XL/BCL-2 inhibitor) on the viability of a panel of 20 SCLC cell lines, which was named as the BH3 mimetic screening [21]. This evidence concerns the gene MCL1 and small cell lung carcinoma.