Fig. 2

Dose-dependent reduction of thymidine kinase 1 (TK1) activity in response to cyclin-dependent kinase 4/6 inhibition in vitro. K562S cells were treated for 6Â h with palbociclib at the indicated concentrations, followed by analysis of cell viability and TK1 activity. TK1 activity was reduced in a linear and dose-dependent manner in response to palbociclib prior to changes in cell viability. Du/L DiviTum units per liter