AEG-1 expression positively correlates with tumor progression, especially in the metastatic stage, and in vivo studies using nude mice and metastatic models with various cancer cell lines and transgenic and knockout mouse models point out that AEG-1 overexpression induces an aggressive, angiogenic and metastatic phenotype, and AEG-1 knockdown or knockout markedly hampers tumor initiation, growth and metastasis [119,120,121,122,123,124,125,126,127,128]. The gene discussed is MTDH; the disease is cancer.