To check whether the antitumor effect of FeF was associated with its inhibition of TOPK activity, tumor tissues from each group were prepared after 20 days of treatment and analyzed for phosphorylation of TOPK downstream targets (p-ERK1/2 (Tyr202/Tyr204) and p-histone H3 (Ser10)) by H&E and immunohistochemistry analyses. This evidence concerns the gene PBK and neoplasm.