Scientists uncover the intricacies of the 'on/off switch' that creates cell differentiation (image) New York University Share Print E-Mail Caption A. Drawing of the hb gene showing a Bicoid-bound enhancer and the hb promoter. B. A fly embryo showing hb RNA (blue) at only one end of the embryo. Image Credit Image courtesy of Jia Ling and Stephen Small Usage Restrictions Use in conjunction with this study only. Share Print E-Mail Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.