A recent example of this preferential intracellular attraction is that treatment with ABT-199 or a BCL-XL-specific mimetic induced more cell death in BCL-2 and BCL-XL expressing human small cell lung cancer (SCLC) and AML cell lines than treatment with ABT-263, indicating an intracellular preference for either BCL-2 or BCL-XL, but not both, by ABT-263 [46]. This evidence concerns the gene BCL2 and small cell lung carcinoma.