“…ID family members including ID1, ID2, and ID3 have identified functions in tumor progression, including angiogenesis, invasion, and metastasis (Lyden et al, 1999;Benezra, 2001;Benezra et al, 2001;Folkman, 2002;Ruzinova and Benezra, 2003;, and in other circumstances ID1 and ID2 may function as tumor suppressors in rodents (Itahana et al, 2003;Sikder et al, 2003;Russell et al, 2004). The function of ID4 in tumorigenesis is similarly complex (Beger et al, 2001;Bellido et al, 2003;Chan et al, 2003;Shan et al, 2003;Umetani et al, 2004Umetani et al, , 2005 Jeon et al, 2008). ID4 seems to function as a tumor suppressor in a variety of cancers (Chan et al, 2003;Umetani et al, 2004Umetani et al, , 2005Yu et al, 2005) and is downregulated by promoter hypermethylation in several tumor types (Chan et al, 2003;Umetani et al, 2004Umetani et al, , 2005Yu et al, 2005).…”