Fig. (2).

The complexity of development varies among organisms despite the conserved core of transcription factor genes. In the figure, the most important evolutionarily conserved transcription factors (NK2, MEF2, GATA, Tbx, and Hand) known to control cardiac human cell fates are reported in different classes of organisms. In Nematodes NK2, MEF2, Tbx has been found (internal line); in Cnidaria NK2, MEF2, GATA and Tbx have been found (middle line) while in Antropodos, Cephalochordates, Fish, Amphibians, and Amniotes all the TFs (NK2, MEF2, GATA, and Tbx) are conserved (external circle line).