Our results demonstrated lower levels of glutamine, glutamate, N-acetyl-aspartate, citrulline and proline while higher levels of alanine, tyrosine, and phenylalanine in trastuzumab resistant cells with GATA6 knockout compared with trastuzumab resistant gastric cancer cells, suggesting that GATA6 plays an important role in amino acid metabolisms of trastuzumab resistant gastric cancer cells. Here, GATA6 is linked to gastric cancer.