
In response to energy stress, AMPK, which acts like a gas gauge by sensing how much energy a cell has, puts a damper on cell proliferation. It muffles a cellular protein called raptor (shown in green), which keeps starving cells from dividing. Nuclei are shown in blue and actin, which forms an integral part of the cellular architecture, is shown in red. Credit: Image: Courtesy of Dr. Reuben Shaw, Salk Institute for Biological Studies A team of scientists at the Salk Institute for Biological Studies think they know how many—if not most—living organisms answer this question. They recently showed that when food supplies dwindle, mammals, fruitflies, or frogs probably activate the same ancient cell signaling pathway in order to conserve energy.