CDK8 and neoplasm: On the other hand, selective CDK8/19 inhibitors showed a variety of therapeutic activities in vivo that are not based on the inhibition of tumor cell proliferation, such as suppression of tumor-promoting effects of chemotherapy-induced DNA damage of host tissues [4], selective inhibition of metastatic but not primary growth of colon cancers [3], and potentiation of in vivo effects of doxorubicin [4] or fulvestrant [6].