Consistent with earlier data, we confirmed that patient-derived tumourspheres and CD166+ tumour cells were tumorigenic even when transplanted subcutaneously into mice at low cell numbers, whereas CD166− tumour cells and two normal human primary lung epithelial cell lines (NHBE, human bronchial epithelial cells; and small airway epithelial cells (SAEC)) were completely devoid of this ability (Fig. 1a). This evidence concerns the gene ALCAM and neoplasm.