Summary: During cytokinesis. a contractile ring consisting of unbranched filamentous actin (F-actin) and myosin II constricts at the cell equator. Unbranched F-actin is generated by formin. and without formin no cleavage furrow forms. https://www.spidertattooz.com/CND-Shellac-Field-Fox-0-5-oz-p13562/