Forever young—how stem cells resist change

This 'before and after' image could be thought of as stem cells' equivalent of an advert for anti-wrinkle cream: 'look how cells stay young!' It shows that a molecule called microRNA-142 allows stem cells to remain unchanged, instead of growing into specialised cell types. Given the right conditions, stem cells with low levels of microRNA-142 (green, left) grow into neurons (pink, right). But stem cells with high levels of the molecule (red, left) remain unchanged (blue, right), scientists at EM