BCL2L1 and Thrombocytopenia: This is even a problem with BH3 mimetics: (i) most putative mimetics act through off-target effects and (ii) the bona fide BH3 mimetic ABT-263 antagonizes both Bcl-2 and Bcl-xL, so that inhibition of Bcl-xL activity results in toxic thrombocytopenia in patients.