Oncomodulin is a high-affinity calcium ion-binding protein. It belongs to the superfamily of calmodulin proteins, also known as the EF-hand proteins. Oncomodulin is an oncodevelopmental protein found in early embryonic cells in the placenta and also in tumors. [provided by RefSeq, Jul 2008] see less Oncomodulin is a high-affinity calcium ion-binding protein. It belongs to the superfamily of calmodulin proteins, also known as the EF-hand proteins. Oncomodulin is an oncodevelopmental protein found in early embryonic cells in the placenta and also in tumors. [provided by RefSeq, Jul 2008]