Beyond its presence on the cell surface, prominin-1 has been detected in intracellular compartments such as endosomes and the Golgi apparatus of various cancer and non-cancer cell lines (e.g., Caco-2, Huh-7, SK-N-DZ, FEMX-I, ARPE-19 cells), and tissue samples [75, 92, 181, 373, 399–401]. This evidence concerns the gene PROM1 and cancer.