CD73 luciferase reporter assays. (a) The orientation of the HIF-1 and CREB binding sites in the CD73 luciferase reporter constructs and the location of truncations used for transient transfections (see Methods for details). WT, wild-type. (b) Confluent BAE monolayers were transiently transfected with plasmids expressing sequence corresponding to full-length CD73 (pGL2^2.0NT, bp –1902 to +63) or to the 5′ truncations pGL2^1.1NT (bp –993 to +63), pGL2^0.57NT (bp –518 to +63), or pGL2^0.15NT (bp –92 to +63), as well as with the SV40 promoter upstream from the luc reporter gene. Twelve hours later, cells were exposed to hypoxia or normoxia for 48 hours and assessed for luciferase activity. All transfections were normalized to cotransfected β-galactosidase activity. Data are mean ± SEM from three separate experiments.*P < 0.01, significantly different from normoxia; **P < 0.025, significantly different than other hypoxia conditions.