Fluorescent light micrograph of cultured human cancer cells showing the stages of mitosis (nuclear division) and cytokinesis (cell division). Mitosis is the formation of two daughter nuclei from one parent nucleus. Fluorescent markers have been used to highlight DNA (deoxyribonucleic acid, blue), alpha tubulin (red), a component of microtubules, and pericentrin (green/yellow), a component of the centrosome. The cycle progresses clockwise from bottom centre where the cell is in interphase and its nucleus clearly visible. At prophase, the nuclear envelope dissolves and the chromosomes condense. The cell progress through prometaphase to metaphase, where the chromosomes align along the centre of the cell. The chromosomes start to move to the opposite poles, guided by microtubules, during anaphase A and anaphase B. The last stage of mitosis is telophase, when the separated chromosomes have moved to opposite ends of the cell and two new nuclei form around them. Cytokinesis divides the cytoplasm of the cell in two, separating the cells.