Fig. 6.

Model of Tbx2 function for the EC formation in the AVC. The mTbx2 misexpression induces expression of Has2; thereby, driving the synthesis and deposition of HA and/or cardiac jelly through the heart. Misexpressed Tbx2 signals also promoted expression of Tgfβ2 gene that supports the induction of EMT in the ventricles and atria. In the normal heart development, Tbx2 works as one of the important factor to induce expansion of ECM and EMT under the Bmp2/4-Smad signaling pathway. Bmp signals also directly to the En through the Bmpr1a.