In cell-based therapy, residual undifferentiated iPSCs can form teratomas unless rigorous purification and suicide-gene safeguards are employed; for example, a paper demonstrated that purifying hESC-derived pancreatic progenitors based on the surface marker glycoprotein 2 (GP2) completely eliminates teratoma risk and yields functional, glucose-responsive β cells after transplantation. This evidence concerns the gene GP2 and teratoma.