Cell Division (IMAGE) Harvard Medical School Caption Both the cell-free egg extract system and embryos recruit critical signaling molecules necessary for cytokinesis signaling. In these micrographs, fluorescently labeled microtubules are green and Aurora B, the cytokinesis signal, is red. Credit Mitchison Lab Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.