CDK7 and cancer: Given that CDK7 inhibitors such as THZ1 and SY-1365 selectively target cancer cells with elevated transcription [25, 26] and that other covalent inhibitors (SY-5609, Q901, and XL102) are in clinical trials [2, 27, 28], understanding the mechanisms and dynamics of CDK7-mediated regulation of splicing and transcription is of high importance.