Acting as intercellular signals, Wnt proteins regulate the proliferation of cells. Wnt signals are active in numerous contexts, initially in early development and later during the growth and maintenance of various tissues. In comparison to other growth factors, Wnt signals have several unique properties, including a short range of action. Thereby, Wnts predominantly mediate signaling locally, between neighboring cells. In addition, Wnt signals give shape to tissues as cells are proliferating. This is a consequence of the ability of Wnt signaling to confer polarity and asymmetry to cells. Wnt proteins are highly conserved in evolution and are active in every branch of the animal kingdom.