Controls cell proliferation in a tissue-specific manner and is involved in morphogenesis. During embryonic development, exerts a role in the expansion of muscle progenitors. May play a role in the proper localization of asymmetric organs such as the heart and stomach (By similarity). Interacts with PITX2. Expressed in the brain. Phosphorylation at Thr-97 impairs its association with the CCND1 mRNA-stabilizing complex thus shortening the half-life of CCND1. Belongs to the paired homeobox family. Bicoid subfamily.