Parthenolide has been reported to inhibit DNMT1 (DNA (cytosine-5)-methyltransferase 1) activity as well as decrease DNMT1 expression which is linked to the decrease the global DNA methylation, leading to hypomethylation and activation of the HIN-1 tumor suppressor gene in cellular model of leukemia and breast cancer [111]. The gene discussed is DNMT1; the disease is breast cancer.