These experiments have shown that Cerberus helps to keep Nodal from crossing to the right side of the developing embryo, allowing left and right asymmetry to form.

Cerberus (Cer) is a gene that encodes a cytokine (a secreted signaling protein) important for induction and formation of the heart and head in vertebrates.

[15][16][7] The Cerberus gene encodes a polypeptide that is 270 amino acids in length and is expressed in the anterior domain of a gastrula in the endoderm layer.

The cerberus-related cytokines, together with Dan and DRM / Gremlin, represent a group of bone morphogenetic protein (BMP) antagonists that can bind directly to BMPs and inhibit their activity.

[5] In human embryonic development, Cerberus and the protein coded by GREM3 inhibit NODAL in the Wnt signaling pathway during the formation of the germ layers.

Specifically, Cerberus and GREM3 act as antagonists to Nodal in the anterior region of the developing embryo, blocking its expression and halting the progression of the primitive node.

[11] Anterior-posterior patterning by Cerberus is accomplished by acting as an antagonist to nodal, bmp, and wnt signaling molecules in the anterior region of the vertebrate embryo during gastrulation.

Misexpression experiments show that lack of Cerberus expression on the right side can result in situs inversus and cardiovascular malformations.

[19] Cerberus plays a vital role in heart development and differentiation of cardiac mesoderm through activation of Nodal signaling molecule.

[13] The heart is developed asymmetrically using the left-right patterning induced by Cerberus which creates a higher concentration of signaling molecules on the left side.

Experiments that inhibited Cerberus led to a loss of left-right polarity of the heart, which was shown by bilateral expression of left side-specific genes.

While the Nodal pathway is found in deuterostomes and protostomes, a proposed common ancestor called Urbilateria has been theorized to be the progenitor of all bilaterally symmetrical animals.

[25] Pigs also lack this ciliary mechanism, but both species rely on an ion pump to accomplish L-R distribution of Nodal.