metastasis suppressors can potentially block metastasis and improve survival. The promoter region of NM23 contains glucocorticoid response elements that can elevate NM23 expression. Treating human breast cancer cells with dexamethasone medroxyprogesterone acetate (MPA) increases NM23 expression. Genes Genes for about a dozen metastasis-suppressing proteins are known in humans and other animals, including BRMS1, CRSP3, DRG1, KAI1, SDPR, KISS1, NM23 and various TIMPs. Most act by altering aspects of signal transduction. NM23 is a suppressor active in melanoma, breast and colon cancers and apparently inhibits the functioning of a kinase enzyme that promotes cell division. NM23 has eight family members. NM23-H1 and NM23-H2 suppress metastasis in multiple tumor types. NM23 expression can serve as a potential prognostic marker for survival in breast, ovarian, melanoma, gastric, hepatocellular and non-small cell carcinoma. It affects the MAPK and cytoskeleton-organizing cellular pathways, which contribute to its metastasis-suppressing functions. MKK4 is a suppressor active in prostate and ovarian cancers It apparently functions by facilitating apoptosis, or death of abnormal cells such as cancer cells. KAI1 is found in prostate and breast cancers. It forms complexes with proteins called integrins. Integrins link cells together. The complex formation may inhibit detachment and migration of cancer cells. BRMS1 promotes the activity of the gap junctions of cells. BRMS1 suppresses metastasis in multiple tumor types including ovarian, bladder, melanoma and non-small cell lung carcinoma. Clinically BRMS1 expression correlates with survival in breast cancer and non-small cell lung carcinoma. SDPR functions as a metastasis suppressor in breast cancer, potentially by priming cells to apoptosis. Cancer cells suppress the gene via promoter DNA methylation hence exemplifies the significance of epigenetic changes in cancer progression. KISS1 is found in melanoma and breast cancers. It acts by synthesizing a protein receptor. RHoGD12 is active in bladder cancer and inhibits proteins that aid in cancer cell migration. RhoGDI2 suppresses endothelin 1 (ET1), a vasoconstrictor correlated with higher clinical stage in bladder cancer. CRSP3 and VDUP1 are both active in melanoma. CRSP3 is a co-activator of genes involved in cancer growth, while VDUP1 inhibits a protein involved in cell proliferation. Ectopic expression of Krüppel-like factor 17 (KLF17) in highly metastatic 4T1 cells suppresses their metastatic potential without affecting primary tumor growth in a mouse model. KLF17 suppression promotes tumor cell epithelial-mesenchymal transition (EMT), which leads to metastasis. Transcription factor Id1 is a direct target of KLF17 and mediates its metastatic functions. KLF17 expression is significantly downregulated