Cmpd3 and Cmpd4 were used in mouse studies of Clarke et al. at doses ranging from 20 to 100 mg/kg [13], in striking contrast to 0.16 mg/kg dose used in leukemia models with cortistatin A [10], a CDK8/19 inhibitor with similar potency to Cmpd3 and Cmpd4. Here, CDK8 is linked to leukemia.