Norcantharidin (NCTD), a demethylated form of cantharidin, has profound anticancer activity against many kinds of cancer cells, including hepatocellular carcinoma [16], prostate cancer [17], and bladder cancer [18] et al. Previously researches demonstrated that NCTD induces degradation of the Cdc6 protein in cancer cells [19, 20] and Xenopus cell-free extracts system [9]. Here, CDC6 is linked to cancer.