“…Stem-like functions of CSCs inherited from their normal stem cells counterparts may be critical for survival during long periods of time in tissues (Hsieh et al, 2007;O'Brien et al, 2010;Rajan et al, 2009;Rosen & Jordan, 2009;Vermeulen et al, 2008;Witte, 2009). In this regard, the generation of cancer cells and their success in tumor growth are probably dependent on dysregulations affecting cells with stem-like characteristics and have the ability to promote tumor and support tumor development (Dalerba et al, 2007;Lang et al, 2009;Weissman et al, 2001). In www.intechopen.com fact, malignant tumors, like normal tissue, frequently contain cells at various stages of differentiation, a mechanism that mimics dedifferentiation of mature cell types and presumes a hierarchical organization (Clarke et al, 2006;Clevers, 2005 …”