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. Isoform PTX2C is involved in left-right asymmetry the developing embryo (By similarity). Interacts with PITX2. Phosphorylation at Thr-90 impairs its association with the CCND1 mRNA-stabilizing complex thus shortening the half-life of CCND1. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the paired homeobox family. Bicoid subfamily.