Protein transduction domains (PTDs), such as TAT from human immunodeficiency virus (HIV) or VP22 from herpes-simplex-virus-1, have been shown to deliver a myriad of molecules, including synthetic small molecules, peptides and proteins in vivo and in vitro. The protein transduction processes mediated by TAT or VP22 are highly efficient and occur in many types of cells with low toxicity. The anti-tumor proteins to be investigated are abrin A chain (ABR-A) and Apoptin. ABR-A is the toxophoric subunit of plant toxin abrin from the seeds of Abrus precatoriusa. ABR-A is a potent inhibitor of translation, but not toxic to cells due to its lack of the cell-binding B chain. Apoptin is a protein derived from chicken anemia virus and has been proved to be selectively cytotoxic to various tumor cells but not to normal cells. The tumor-specific activity of Apoptin is correlated with its nuclear localization in tumor. In this study, we employed VP22 PTDs to promote the entry of natural toxins, such as ABR-A or Apoptin, into tumor cells, thereby to enhance their anti-tumor effects. We generated and characterized green fluorescent protein (GFP)-, hemagglutini (HA)-, and VP22-fused expression constructs for ABR-A and Apoptin, to evaluate the gene delivery effect of ABR-A/Apoptin genes in non-transformed NIH3T3 cells and tumor cells, including Hela and A375 melanoma cells. Gene delivery of ABR-A led to growth inhibition by 50~70% in transformed and non-transformed cells. In contrast, Apoptin gene delivery exhibited cytotoxicity only in tumor cells. The cytotoxicity of ABR-A and Apoptin gene delivery was enhanced when fused with VP-22. Furthermore, the depletion of APAP1 reduced the cytotoxic effect of Apoptin gene delivery. In the future, the anti-tumor effect of these novel PTD-toxin vectors will be explored in cell culture as well as animal model. We hope these studies will open a new avenue for cancer therapy.