For liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis of mouse pancreatic cancer cells, we injected green fluorescent protein (GFP)-labeled KPC cells into the pancreases of C57BL/6J mice to establish orthotopic pancreatic cancer models. Following stress treatment, we isolated the GFP-labeled pancreatic cancer cells from the allografts of the stress-treated or control C57BL/6J mice. Subsequently, we conducted protein mass spectrometry on these GFP-labeled tumor cells.