CDK9 and B-cell chronic lymphocytic leukemia: We compared the time and dose dependence of responses of CLL cells to different agents that inhibit transcription, including the CDK9 inhibitors dinaciclib [39–42], flavopiridol [7, 43], roscovitine [44–46], SNS-032 [8, 47, 48], and fadraciclib, as well as dactinomycin, which interferes with the elongation of growing RNA chains by intercalating into DNA [49].