Dyrk inhibitor Mirk-IN-1 had an EC50 of 1.9 ±0.2 mmol/L on SW620 cells. Mirk-IN-1 inhibited the activities of DYRK1A, ABL, FLT3, and MARK1 by 88%, 64%, 56%, and 73%, respectively, at a much higher concentration of 10 mmol/L in a kinase assay [1]. Mirk-IN-1 was able to block tumour cells from undergoing reversible arrest in a quiescent G0 state and enable some cells to exit quiescence [2].