ESR2 and gastric cancer: Helicobacter pylori activates ERBB2 through the production of cytotoxins, which can lead to aberrant signaling, inflammation, and increasing gastric cancer risk, forming homo-dimers or hetero-dimers, which activate phosphorylation cascades within the cell, in turn leading to activation of Erb and MAPK signaling pathways, driving proliferation and survival of cancer cells [120].