Hypoxia is an almost universal hallmark of solid tumors. Adaptation to hypoxia is critical for tumor survival and growth, and is mediated largely by transcriptional activation of genes that facilitate short - (e.g., glucose transport) and long - term (e.g., angiogenesis) adaptive mechanisms. This coordinated homeostatic response is mediated in large part through the activation of the heterodimeric transcription factor hypoxia - inducible factor 1 (HIF - 1). Under conditions of normal oxygenation, the regulated HIF - 1α is hydroxylated and degraded by the proteasome system. As oxygen becomes rate limiting, hydroxylation diminishes and HIF - 1α accumulates and heterodimerizes with the constitutively present α - subunit. The binding of this complex to the cognate hypoxia - response element (HRE) results in transcriptional activation of genes containing such elements within promoter or enhancer elements. The CellSensor® HRE-bla HCT - 116 Cell Line contains a beta - lactamase reporter gene under control of the HRE stably integrated into HCT - 116 cells. This cell line is validated for EC50 and Z'; - factor under optimized conditions using deferoxamine (DFO) and Cobalt Chloride. This cell line has also been tested under various experimental conditions, including DMSO concentration, cell number, stimulation time, and substrate loading time. CellSensor ® HRE-bla HCT - 116 cells were stimulated with deferoxamine (DFO) over the indicated concentration range in a 384 - well format. Cells were incubated for 24 hrs with agonist and 0.5% DMSO and then combined with LiveBLAzer™ - FRET B/G Substrate (CCF4 - AM) for 2 hrs. Fluorescence emission values at 460 nm and 530 nm were obtained using a standard fluorescence plate reader. The Response Ratios were plotted against the indicated concentrations of DFO. CellSensor® HRE - bla HCT - 116 cells were stimulated with Cobalt Chloride (CoCl2)over the indicated concentration range in a 384 - well format. Cells were incubated for 24 hrs with agonist and 0.5% DMSO and then combined with LiveBLAzer™ - FRET B/G Substrate (CCF4 - AM) for 2 hrs. Fluorescence emission values at 460 nm and 530 nm were obtained using a standard fluorescence plate reader. Response ratios were plotted against the indicated concentrations of CoCl2. Academic and non-profit customers, please inquire for special pricing.