MUC5AC and gastric cancer: It has been shown that the activation of PI3K (Phosphoinositide 3‐kinase) through the ErbB2 (Her2)/ ErbB3 (Her3) pathway in signet ring cells could enhance mucin secretion.23 Additionally, the adherent junction is disrupted via activation of the Mitogen‐activated protein kinase 1 (MEK1) pathway, which leads to the loss of cell‐cell contact.24 Further, it has been reported that signet ring cells were more likely to have transcoelomic metastasis than other gastric cancer cells.2, 25 These findings could explain the high frequency of metastasis and reoccurrence in gastric SRCC.