KRAB Silencing Activity in Target Gene (VIDEO) California Institute of Technology This video is under embargo. Please login to access this video. To view this video please enable JavaScript, and consider upgrading to a web browser that supports HTML5 video Caption By combining synthetic biology approaches with time-lapse movies that track the behaviors of individual cells, a team led by Caltech biologists has determined how four members of a class of proteins known as chromatin regulators establish and control a cell's ability to maintain a particular state of gene expression. In this movie, recruitment of KRAB (one of the four regulators tested by the group) completely silences, or turns off, the target gene, which codes for a fluorescent protein. Cells with active genes appear green. Note that most cells go dark within a narrow window of time. Credit L. Bintu, J. Yong, and M.B. Elowitz / Caltech Usage Restrictions None License Licensed content 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.