Disclosed is a use of a SUSD2 protein as a marker, in particular a use of the SUSD2 protein as the marker in identification, selection or separation of pancreatic internal secretion precursor cells and/or newborn pancreatic internal secretion cells； and a use of an mRNA, for encoding the SUSD2 protein, of a precursor protein as the marker in identification of the pancreatic internal secretion precursor cells and/or the newborn pancreatic internal secretion cells. Through analysis of gene expression of pancreatic endoderm cells sourced by induced directional differentiation of human pluripotent stem cells, the enrichment expression of a SUSD2 gene in the pancreatic internal secretion precursor cells and the newborn pancreatic internal secretion cells is found. In addition, a protein encoded by the SUSD2 gene is a receptor protein on cell membranes. Using the protein as the marker, the identification, the selection or the separation of the pancreatic internal secretion precursor cells and the newborn pancreatic internal secretion cells can be carried out, which has an important significance on research about pancreas related cells in each development stage.
