TNF and neoplasm: Utilising tumour-targeting systems with the non-pathogenic E. coli strain, MG1655 induced targeted production of TNF-α in mouse tumours, which demonstrated the tumour-suppressive effect.312 In two other mouse studies, the expression of cytolysin A (Cly A) in E. coli or S. typhimurium was regulated by inducible or constitutive promoters, achieving localisation to tumour tissue.313,314 Engineered bacteria can enhance antitumour activity by stimulating immune responses.