TLR4 and gastric cancer: It is becoming increasingly clear that several specific host genes, such as PGC (pepsinogen C), PTPN11 (protein tyrosine phosphatase, non-receptor type 11), TLR4 (Toll-like receptor 4), and IL1B (interleukin-1B), are involved in the response to H. pylori infection and are currently identified as susceptibility genes for gastric cancer [6, 7].