The Mediator kinase CDK8 and its paralog CDK19, together with their binding partner Cyclin C (CCNC), have been implicated through experimental studies in several malignancies, including cancers of the colon [1,2,3], breast [4,5,6,7], prostate [8], pancreas [9], melanoma [10], and leukemias [11,12]. The gene discussed is CDK8; the disease is leukemia.