Interestingly, CXXC4 was downregulated by polymyxin B but upregulated by FADDI-251 or FADDI-287, indicating that apoptosis could be induced by polymyxin B. Furthermore, on the one hand, CXXC4 could be used as an indicator for polymyxin toxicity, while on the other hand, the less toxic polymyxin analogues could be considered anti-tumor drugs by targeting CXXC4. This evidence concerns the gene CXXC4 and neoplasm.