HIF-1 α plays a role in replication as well as transcription
Its expression is regulated at the transcriptional level, as well as by modulators of its translation and degradation. HIF-1 α then regulates the expression of a variety of genes that allows cells to survive in changing oxygen conditions.
A recent article in Science Signaling suggests additional functions for this regulator of hypoxic survival. In 'A Nontranscriptional Role for HIF-1α as a Direct Inhibitor of DNA Replication' the authors describe how, during hypoxia, HIF-1α bound to a complex essential for firing of replication origins and decreased the phosphorylation and activation of this complex despite an increase in association of the complex with chromatin. The results is cell cycle arrest that results from HIF-1α stabilization which is independent of transcription.
If you are interested in performing cell-based analysis in different oxygen conditions, the atmospheric control unit available with the Omega series of microplate readers from BMG LABTECH could be a useful tool.