T Cell Marker (image) Max-Planck-Gesellschaft Caption Using a calcium sensor shows that the calcium concentration in T cells (green) changes when it interacts with dendritic cells (red) [top]. The activation of the T cell (red) can be illustrated by the migration of the NFAT signal protein (green) from the cell plasma to the cell nucleus [bottom]. Credit MPI of Neurobiology Usage Restrictions None 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.