Pulmonary artery cells. Fluorescence deconvolution micrograph of cultured cells from a pulmonary artery undergoing cytokinesis (cellular division). The cell nuclei, which contain the cells' genetic information, are blue. Actin protein filaments, which make up part of the cytoskeleton, are green. The cytoskeleton maintains the cells' shape, allows some cellular mobility and is involved in intracellular transport. Mitochondria, which produce energy for the cell, are red.