Fig. 4.

Hypoxia represses ER activity. E₂ (−) is estrogen-free media (phenol red-free DMEM with 10% charcoal stripped FBS). E₂ (+) is phenol red-free DMEM with 10% charcoal stripped FBS supplemented with 10 nM estradiol. a ER transcriptional activity analyzed at normoxia or at 48 h of 1% O₂ using an ERE-directed luciferase reporter construct [35]. (MCF7: *p = 0.043, BT474: *p = 0.004, T47D: *p = 0.032, ZR75B: *p = 0.001). b qPCR analysis of mRNA levels for endogenous PRG mRNA transcripts at normoxic or hypoxic conditions (1% O₂, 24 h). Relative mRNA levels normalized to TBP. (MCF7: *p = 0.049, BT474: *p = 0.014, T47D: *p = 0.032, ZR75B: *p = 0.047). c ER activity analyzed in control cells or cells transfected with a stabilized HIF-1α allele (HIF-1αODD) using an ERE-directed luciferase reporter construct [35]. (MCF7: *p = 0.036, BT474: *p = 0.034, T47D: *p < 0.001, ZR75B: *p = 0.026)