Tbx20 regulation of cardiac cell proliferation and lineage specialization during embryonic and fetal development in vivo

► Tbx20 promotes cell proliferation and Bmp10/pSmad in fetal cardiomyocytes. ► Tbx20 promotes cardiac conduction system gene expression in fetal myocardium. ► Tbx20 inhibits cell proliferation and induces p21 in embryonic cardiomyocytes. ► Tbx20 inhibits dpERK1/2 activation in embryonic cardiomyocytes.