CDK9 and neoplasm: The MYC family encoded transcription factors containing six highly conserved regions, termed MYC homology boxes (MBs), among them, MB0 directly interacts with TFIIF in a transcription elongation complex, containing CDK9 and Pol II, MB0 is dispensable for tumor initiation but is a major accelerator of tumor growth (Kalkat et al., 2018).