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Function of Myosin IIB in Maintaining Cell Shape and Polarity

Lo et al., Mol. Biol. Cell 15:982-989 (2004)

Myosin II is known to interact with actin filaments to generate contractile forces. However the function of such forces in non-muscle cells is poorly understood. This question was addressed by observing the behavior of mouse embryonic fibroblasts where the expression of one of the myosin isoforms, myosin IIB, was inhibited by gene ablation.

Myosin IIB Knockout Fibroblasts Show Highly Irregular Shapes And Uncoordinated Movements

Myosin IIB knockout fibroblasts typically show multiple protruding edges and branches. These cells fail to coordinate frontal protrusion and tail retraction for directional movements. Instead, tips of protrusion often "walk" away from the rest of the cell to form cytoplasmic fragments. Some fragments remain tethered to the cell through invisible strands (above the cell), others appear to be totally detached (near the top edge). Recording time, 91 min.