In particular, it has been demonstrated that overexpression of CLOCK enhances the expression of genes related to angiogenesis, including vascular endothelial growth factor (VEGF), hypoxia-inducible factor 1-alpha, (HIF1α), and basic helix-loop-helix (BMAL1), which is a tumor suppressor (Figure 2). This evidence concerns the gene HIF1A and neoplasm.