To address the question of cell-of-origin for these oesophageal cancers, we transformed Barrett's and oesophageal stem cell pedigrees in vitro using identical protocols27 involving retrovirally transduced SV40 large T antigen, c-Myc and hTERT and then injected them into NSG (NOD.Cg-PrkdcscidIl2rgtm1Wjl/SzJ) mice28 (Fig. 4a). Here, CTSG is linked to carcinoma of esophagus.