The mode of action of eudesmane SLs involves perturbation of MT stability at the levels of both tubulin polymerization and depolymerization, and upregulation of p-Cdk1 (Tyr15) and cyclin B1 in leukemia (CCRF-CEM murine), breast cancer (MCF-7), and hepatoma (HA22T/VGH) cells. Here, CDK1 is linked to breast cancer.