 The increase of BMP4, Xnr1, Xwnt8 and the decrease of Cerberus together blocked the formation of the head.This gene knockdown experiment showed the necessity of Cerberus’ inhibitory functions in the formation of head structures.It quite possibly may be that although Cerberus is necessary for the induction of a head, its inhibitory actions may play a more significant role in ensuring the head is developed properly.