Arsenite not only is widely used for cancer therapy, but also is a well-recognized human environmental carcinogen, further more mechanisms studies on the function of the p50 will not only shed insight into understanding of the molecular basis for its carcinogenic effect, but may also provide insight into researching of arsenite-p50 downstream mediators and effectors as a potential target for cancer prevention and therapy. This evidence concerns the gene NFKB1 and cancer.