HSPG2 and gastric cancer: TFF peptides (TFF1, TFF2, and TFF3) are involved in several steps of gastric cancer development through multiple oncogenic pathways and are considered to be potential tumor suppressor genes, including PI3-kinase, phospholipase C (PLC), MAPK, PKC, and the rapamycin target mTOR, but also EGF-R, COX-1, COX-2, and G-protein coupled receptors [33,34,35,36].