There are a few processes in a cell that simply blow my mind as I try to grasp how such a complex task is accomplished correctly every time. Cytokinesis is one of them, and is an absolutely elegant process to watch.
Cytokinesis is the step during cell division that physically splits a cell in half. Cytokinesis depends on actin, myosin, and many regulatory proteins, and a recent paper helps sort out where and how these proteins interact. Image above shows two cells undergoing cytokinesis, with microtubules remaining from the mitotic spindle (red), chromosomes (blue), and an actin-nucleating factor called mDia2 (green). The control cell (top) shows mDia2 localization at the cleavage furrow, the indentation of membrane at the beginning of cytokinesis; however, without a protein that regulates an mDia2 activator, mDia2 levels are reduced at the cleavage furrow.
Reference: Sadanori Watanabe, Katsuya Okawa, Takashi Miki, Satoko Sakamoto, Tomoko Morinaga, Kohei Segawa, Takatoshi Arakawa, Makoto Kinoshita, Toshimasa Ishizaki, and Shuh Narumiya. Authors’ Molecular Biology of the Cell paper can be found here.