Microinjected F-actin into dividing newt eggs moves toward the next cleavage furrow together with Ca2+ stores with inositol 1,4,5-trisphosphate receptor in a microtubule- and microtubule motor-dependent manner.

It has been reported that F-actin is transported to the presumptive cleavage furrow along the cortex during anaphase-cytokinesis, an event termed cortical actin flow in animal cultured cells. The motor source has remained unknown. We reported that Ca2+ stores with IP3 receptor (IP3R) was re-distributed from the polar cortex during metaphase to the presumptive cleavage furrow just before the onset of furrowing, and that Ca2+ stores with IP3R microinjected into dividing newt eggs moved toward the presumptive cleavage furrow during anaphase-cytokinesis in a microtubule-dependent manner, and that Ca2+ store-enriched microsome fractions induced the cleavage furrow as the putative cleavage stimulus.