In this colorized micrograph, immune cells called macrophages (purple) and T cells (red) isolated from a live mouse tumor interact through the T cell receptor (green).

tip of an electrochemical nanosensor positioned at the invagination of the phagocytal sac of a RAW 264.7 mouse macrophage after 12 h of inhibited phagocytosis; scale bar, 10 μm.