This Review is the introduction of a new thematic series on Wnts in Cardiovascular Development and Disease, which includes the following articles: An Updated Overview on Wnt Signaling Pathways: A Prelude for More [2010;106:1798–1806] The Multiple Phases a

Abstract: Understanding heart development on a molecular level is a prerequisite for uncovering the causes of congenital heart diseases. Therapeutic approaches that try to enhance cardiac regeneration or that involve the differentiation of resident cardiac progenitor cells or patient-specific induced pluripotent stem cells will also benefit tremendously from this knowledge. Wnt proteins have been shown to play multiple roles during cardiac differentiation and development. They are extracellular growth factors that activate different intracellular signaling branches. Here, we summarize our current understanding of how these factors affect different aspects of cardiogenesis, starting from early specification of cardiac progenitors and continuing on to later developmen-tal steps, such as morphogenetic processes, valve formation, and establishment of the conduction system. (Circ Res. 2010;107:186-199.) Key Words: Wnt cardiac differentiation cardiac development Wnt proteins are growth factors that function duringembryonic development and in the adult organism by regulating diverse cellular processes such as gene transcrip-tion and cell proliferation, migration, polarity, or division.1 Not surprisingly, Wnt proteins are also involved in cardiac development and differentiation. To understand the functio