PROM1 and cancer: Therefore, the discovery of prominin-1-a isoform from octopus ink as well as bioactive peptides (CCCRCCNRCGGRHMKY, IVLYFIGYSICVAIGILFIILIPLIGCCLCCCR, TYVTCLVILNTIILFAVVCTFITNELYK, SVAVPCSVLLLWILIAFSLVDHSFAQNSSQQHR) from this protein may open up new opportunities for cancer and stem cell studies.