CDK12-IN-4, a pyrazolotriazine compound, exhibits potent inhibition of CDK12 by achieving an IC50 value of 0.641 μM, utilizing high ATP levels (2 mM). Notably, CDK12-IN-4 does not impact CDK2 Cyclin E (IC50 > 20 μM) or CDK9 Cyclin T1 (IC50 > 20 μM) under the influence of high ATP (2 mM) levels (WO2021116178A1).