Epigenetic reprogramming is done by modifications to the epigenome which is a layer of information that regulates when genes need to be expressed. By altering aspects of certain proteins, it is possible that a scientist can rewind the biological clock of a cell. This has yielded encouraging results in mice, and hints at the possibility of reversing aging in cells. This is an active area of active research, and is considered a good target for anti-aging therapies.