The anti-metastasis effect of K5 is likely to be mediated by suppressing the protein stabilization and nuclear accumulation of HIF-1α, consequently inhibited the HIF-1α transcriptional activity that could be responsible for decreasing gene expression of VEGF and CXCR4, resulting in the inhibition of angiogenesis and tumor chemotaxis movement which are indispensable steps in the progression of metastasis (Fig. 8). The gene discussed is HIF1A; the disease is neoplasm.