As an additional mechanism, phosphorylation of the RNAP II CTD residues serine 2 (p-RNA II ser2) was inhibited in a dose-dependent manner after treatment with CDK9 inhibitor, which is consistent with previous reports on colon carcinoma and adult T-cell leukemia/lymphoma 15, 37. The gene discussed is CDK9; the disease is adult T-cell leukemia/lymphoma.