The fibroblast activation protein 2 protein of F. nucleatum combines with TIGIT in the pancreas 130, regulates the tumor microenvironment, reduces CD3+ T cells and CD4+ T cells, increases M2-like TAMs, suppresses the attack of the immune system on tumor cells, and promotes the development of pancreatic cancer 188. This evidence concerns the gene CD4 and familial pancreatic carcinoma.