HTATIP2 and lung adenocarcinoma: Since subcutaneous lung tumor xenografts have been shown to exhibit significant hypoxia when compared with orthotopic lung tumor xenografts and spontaneous lung tumors [36], a subcutaneous A549 human lung adenocarcinoma xenograft model was used in the present study to explore the modulatory effect of the absent expression of HTATIP2 on tumor adaptation to hypoxia and associated mechanisms.