Harvested A549 tumor xenografts at the end of in vivo study revealed that increased didymin-mediated apoptosis correlated with the results of the in vivo anti-tumor study, therefore, didymin is involved in the Fas/FasL apoptotic system in the anti-proliferative effects of cancer cells, resulting in increased apoptosis and apparent anti-tumor property. This evidence concerns the gene FAS and neoplasm.