HeLa cells expressing the protein survivin

Fluorescence micrograph of a cluster of cells expressing the protein survivin (green). Cell nuclei (blue) and mitochondria (red) are also visible. Survivin is essential for regulating the cell cycle and promoting cell survival. It plays a role in assisting the correction of misaligned chromosomes during cell division. Survivin also protects against caspase-mediated cell death. Survivin is normally only expressed during part of the cell cycle (G2/M phase), but in some cancer cells it is present throughout the whole cell cycle correlating with resistance to radio and chemotherapy. Fluorescence micrograph; x 40; nuclei of survivin-expressing cells are approximately 15 micrometers in length.