Natural Killer Cell (IMAGE) Columbia University Irving Medical Center Caption A 3-dimensional model of a natural killer cell (purple) with granules (yellow) attaching to a target cell (gray). A pseudo color scale shows differences in packing density of lipids on NK cell membrane, with warmer colors indicating higher density. Credit Orange lab, CUIMC Usage Restrictions With permission from CUIMC License Original 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.