Osteosarcoma cells. Immunofluorescence light micrograph of human osteosarcoma cells stained to show cell proteins and organelles. The stains used here have highlighted the structural protein tubulin (green), the stress responsive protein and enzyme sirtuin 6 (SIRT6, red), and mitochondria (blue). SIRT6 is linked to aging, sugar metabolism, and inflammation. Mitochondria are the energy-producing cell organelles. Osteosarcoma is a type of bone cancer. Magnification: x1030 when printed at 10 centimetres wide.