ABT-737 is a BH3 mimetic inhibitor of Bcl-xL, Bcl-2 and Bcl-w with EC50 of 78.7 nM, 30.3 nM and 197.8 nM, respectively, showing no inhibition observed against Mcl-1, Bcl-B or Bfl-1.

ABT-263 is a potent inhibitor of Bcl-xL, Bcl-2 and Bcl-w with Ki of ≤ 0.5 nM, ≤1 nM and ≤1 nM in cell-free assays, but binds more weakly to Mcl-1 and A1.

Gambogic acid activates caspases with EC50 of 0.78-1.64 μM and competitively inhibits Bcl-XL, Bcl-2, Bcl-W, Bcl-B, Bfl-1 and Mcl-1 with IC50 of 1.47, 1.21, 2.02, 0.66, 1.06 and 0.79 μM, respectively.