We reported that (–)-xanthatin abrogated the proliferation of highly aggressive breast cancer MDA-MB-231 cells via mechanisms involving (i) Topoisomerase IIα (Topo IIα) catalytic inhibition (i.e., accumulation of DNA damage) and (ii) the production of reactive oxygen species (ROS), which result in the re-activation of GADD45G expression; thus, (–)-xanthatin may be a selective inducer of GADD45G [3,4]. The gene discussed is GADD45G; the disease is breast cancer.