Studies have demonstrated that emodin decreased the expression of c-Jun due to the reduction of adenosine 5′-monophosphate (AMP)-activated protein kinase-alpha and the inhibition of COP9 signalosome-associated kinases, which contributed to the anti-cancer effects of emodin (Füllbeck et al., 2005; Tang et al., 2015). This evidence concerns the gene JUN and cancer.