Recently DDX3 has been the focus of a great deal of research because of its involvement in the replication of the human immunodeficiency virus, hepatitis C virus, and poxviruses. Recent work indicates that DDX3 can participate in the transcriptional regulation of a diverse set of genes involved in apoptosis and cellular transformation in ways that impact cancer progression. On the other hand, our work has shown that over-expression of DDX3 brought about a cellular transformation leading to the down-regulation of E-cadherin expression in immortalized breast epithelial cells. Down-regulation of E-cadherin is a marker of an epithelial mesenchymal transition phenotype, which is associated with cancer progression in several cancers. We also found that DDX3 expression is directly correlated with tumorigenesis in a panel of breast epithelial cell lines ranging from non-tumorigenic to highly aggressive cancer phenotypes. In MDA-MB-231, a highly aggressive metastatic breast cancer cell line, DDX3 was found within an anti-apoptotic complex consisting of glycogen synthase kinase 3 and cellular inhibitor of apoptosis 1, which is an indication of its importance in the therapeutic resistance of tumor cells to TRAIL receptor antibody therapy. Thus, DDX3 has diverse functions in a variety of cell types, in breast cancer cells DDX3 augments cell proliferation whereas in hepatocellular carcinoma cells it promotes growth arrest and tumor suppressing activities. Hypoxia is a major characteristic of solid tumors and a condition that affects genome-wide changes in gene expression, which greatly impacts cellular and tumor tissue physiology particularly Avitinib maleate inhibitor respiration and metabolism. Expression of hypoxia-responsive genes is predominately regulated by hypoxia inducible factors. HIFs are basic helix-loophelix/ PAS transcription GJ103 sodium salt inhibitor factors consisting of an alpha subunit and a b subunit, i.e., aryl hydrocarbon receptor nuclear transporter. HIF-1 is expressed in most tissues and functions as the principal transcriptional regulator of most HIF responsive element containing genes while HIF-2 exhibits restricted expression and a more limited scope of regulation. Under normoxic conditions, HIF-1a and 2a are subjected to ubiquitination and proteasomal degradation.