roliferation and DNA repair.73 CDK9 paired with cyclin T1 forms the positive transcription elongation factor b (p-TEFb) complex and induces transcriptional activation by hyperphosphorylating RNA polymerase II, and thereby regulating numerous vital cellular functions including proliferation, differentiation, DNA repair and apoptosis.74,75 However, growing studies suggest that CDK9 is also related to many pathologic processes,