CD44 and cancer: In order to prospectively enrich and eventually isolate tumour-initiating cells from the bulk Lin- population of Apc1638N/+/KRASV12G tumours, we first tested a panel of previously established (cancer) stem cell markers including CD24, CD29 (β1 integrin), CD44, CD97, and L1CAM by FACSorting and subsequent transplantation in NOD-SCID mice.