Of note, the selection of tumour initiating cells by this in vivo assay resulted in enrichment of these stem cell markers, over baseline levels in vitro, where differences were 11-fold, 80-fold, 44-fold and 140-fold for ABCG2, Nanog, Notch1 and SOX2 expression, respectively (p<0.05). The gene discussed is ABCG2; the disease is neoplasm.