Inflating cell numbers by Wnt

One of the prominent biological phenomena controlled by Wnt signaling is the expansion of cells with predefined fates. In the November 27, 2002, issue of Cell, Rosenfeld and colleagues describe an example of Wnt-controlled proliferation during genesis of the cardiac outflow tract and the pituitary gland. As a downstream target gene of the Wnt cascade, the bicoid-related transcription factor Pitx2 directly drives proliferation in these tissues (Kioussi et al., 2002).