Considering the unique cytoplasmic translocation method utilized by LF via PA [41], the specificity of the PA/receptor interaction and innate anti-angiogenic properties of LF, and the over-expression of the anthrax toxin receptor TEM-8 in tumor endothelium [63], it is not surprising that some investigators have begun to explore the use of LeTx as a method of tumor therapy [32,42,43]. This evidence concerns the gene ANTXR1 and neoplasm.