Centralspindlin in Rappaport's cleavage signaling

Cytokinesis, the division of the whole cytoplasm, is an essential process for cell proliferation and embryonic development. In animal cells, cytokinesis is executed using a contractile network of actin filaments driven by a myosin-II motor that constricts the cell cortex (cleavage furrow ingression) into a narrow channel between the two daughter cells, which is resolved by scission (abscission) [1], [2], [3]. The anaphase-specific organization of the mitotic apparatus (MA, spindle with chromosomes plus asters) positions the cleavage furrow and plays a major role in spatial coupling between mitosis and cytokinesis [4], [5], [6]. The nucleus and chromosomes are dispensable for furrow specification [7], [8], [9], [10], although they contribute to persistent furrowing and robust completion in some cell types [11], [12]. Likewise, centrosomes are not essential for cytokinesis, but they contribute to the general fidelity of cell division [10], [13], [14], [15]. Here, classical models of cleavage furrow induction are outlined, and a unified view of the stimulation of cortical contractility by the centralspindlin-ECT2 pathway is discussed.