CDK/HDAC-IN-4 is a high selective dual cyclin-dependent kinase ( CDK )/histone deacetylase ( HDAC ) inhibitor with IC 50 values of 88.4 and 168.9 nM, respectively. CDK/HDAC-IN-4 exhibits antiproliferative capacities against hematological and solid tumor cells. CDK/HDAC-IN-4 also induces MV-4-11 cell Apoptosis and S cell cycle arrests. CDK/HDAC-IN-4 possesses a significant antitumor potency in the MV-4-11 xenograft model.