Abstract: Disclosed herein are methods of identifying a gastric cancer stem cell or gastric cancer stem cell population. Also described herein are methods of isolating one or more gastric cancer stem cells from a cell population, comprising contacting cells of the cell population with an agent that binds to AQP5, isolating one or more AQP5-expressing cells that are bound to the agent, wherein the one or more AQP5-expressing cells are gastric cancer stem cells. Further described herein are methods of ablating or eliminating an AQP5+ gastric cancer stem cells, as well as methods of treating gastric cancer, and methods of monitoring gastric cancer tumorigenesis or progression of gastric cancer.