Here, we demonstrated that host CD39 impacts both tumor growth and tumor and normal tissue responses to IR; murine LLC1 lung tumors grew faster on mice with genetic deficiency of CD39 and were more resistant to tumor growth delay induced by single high-dose irradiations, whereas genetic deficiency of CD73 in the tumor host did not significantly alter tumor growth and the response to RT. This evidence concerns the gene ENTPD1 and neoplasm.