TNF and cancer: For example, Bacteroides fragilis can secrete endotoxins that cause DNA damage leading to mutations and cancer development.[5] The activation of mitogen‐activated protein kinase (MAPK), mammalian target of rapamycin, tumor necrosis factor (TNF), and other pathways commonly observed in LC patients is associated with certain microbiota, such as Veillonella and Streptococcus.