Mouse Neurons (IMAGE) Duke University Caption In mice with several different genetic forms of microcephaly, stem cells (shown in red or blue) die off before they can divide and become mature neurons (green). Too much of a protein called p53 is at least partly responsible for underdeveloped brains in each of the mouse models, finds a new study. Credit John McMahon, Duke University 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.