NDRG2 and esophageal squamous cell carcinoma: To investigate the effects of Ad-NDRG2 on tumor growth in vivo, we injected 1 × 109 PFU Ad-NDRG2, Ad-LacZ, or PBS every 3 days into pre-established human Eca-109 ESCC tumours (approximately 200 mm3) grown in nude mice.