EPAS1 and HIF-1β protein levels in Ahrr
+/+, Ahrr
+/- and Ahrr
-/- FaDu cell cultures. A, B. HIF-1β is a member of class II bHLH/PAS protein family, a common binding partner of EPAS1 and AHRR, and an important basis for the interaction between the two signaling pathways. C-E. EPAS1 protein levels were determined by enzyme immunoassay on 10 µg total protein isolated from FaDu cell cultured with normoxia or hypoxia. F-H. HIF-1β protein levels were determined by western blot analysis of 10 µg total protein isolated from FaDu cell cultured with normoxia or hypoxia. Band density was calculated for each protein and expressed relative to GAPDH band density. Data are mean ± SD in triplicates in an independent experiment, which was repeated at least for three times with the same results (P<0.01).