Dactylone was able to suppress the phenotype expression of various human cancer cell lines and was shown to induce G1-S cell cycle arrest and apoptosis in tumor cells; it decreased Rb protein phosphorylation at Ser795, Ser780, and Ser807/811 sites, and also inhibited the expression of cyclin D3 and cyclin-dependent kinase (Cdk)4 [14]. Here, CDK4 is linked to cancer.