Bcl-2-IN-11 (compound 6) is a potent and selective Bcl-2 activity inhibitor, with an IC 50 of 0.9 nM. Bcl-2-IN-11 shows weak inhibition of Bcl-xl ( IC 50 > 1000 nM). Bcl-2-IN-11 can be used for the research of a variety of cancers caused by abnormal overexpression of Bcl-2 family proteins: especially malignant hematologic diseases of acute lymphoid leukemia, etc. Bcl-2-IN-11 can also avoid toxic side effects caused by Bcl-xl inhibition, such as thrombocytopenia.