HDAC9 and cancer: Given that TBX2 was previously implicated in HDAC1 controlled repression of CDKN1A expression and cell cycle arrest in different cancer types20 and the strong observed effects of HDAC inhibitors in combination with other anti-cancer drugs41, we also decided to combine HDAC1 inhibitor Panobinostat together with the CDK7 inhibitor THZ1 (Supplementary Fig. 7c).