 Overexpression or overabundance of Cerberus is associated with the development of ectopic heads.These additional head-like structures may contain varying characteristics of a normal head (eye or eyes, brain, notochord) depending on the ratio of overabundant Cerberus to other proteins associated with anterior development that Cerberus inhibits (Wnt, Nodal, and BMP).If only Nodal is blocked, a single head will still form but with abnormalities such as cyclopia.