The CLDN18/Yes-associated protein (YAP) pathway regulates the homeostasis of normal lung stem and progenitor cells, and its deficiency promotes tumorigenesis and progression of lung and gastric adenocarcinoma.69,85–87 By contrast, CLDN2 activates YAP, leading to self-renewal of human colorectal cancer stem-like cells.88 Since CLDN2 has two conserved pY in the C-terminal cytoplasmic domain as described above, it should also be verified whether CLDN2/SFK signaling is involved in the self-renewal of various cancer stem-like cells. The gene discussed is CLDN2; the disease is gastric adenocarcinoma.