CDK7 and leukemia: We first validated the bioactivity of these small-molecule drugs, the BET bromodomain protein inhibitor JQ1 and its biotinylated derivative JQ1-btn, CDK7 inhibitor THZ1 and THZ1-btn, and the topoisomerase-II inhibitor doxorubicin (Dox) and Dox-btn in both human leukemia K562 and gastric cancer HGC27 cells as well as human CRC organoids (Extended Data Fig. 1a–h).