Figure 9. Both myosin IIA and IIB isoforms are required for the formation of distinct actin network in the spreading cells.

Spreading MDA-MB 231 cells depleted of myosin IIA and IIB were fixed and stained with paxillin antibodies, phalloidin, and DAPI. A) The formation of an organized actin network in the spreading cell expressing myosin IIA and IIB. Arrow-head and filled arrow indicate central fibers and transverse arcs in the scrambled siRNA received spreading cells, respectively. Focal contacts are connected to actin filaments in the lamellipodia and central part of the spreading cell. Loss of an organized actin network especially actin arcs and focal contacts are shown in the spreading cell depleted of myosin IIA. Myosin IIB-depleted cells display loss of transverse arcs and the formation of long actin fibers during spreading. In the spreading margins focal contacts are connected to these long actin filaments. The scale bars represent 20 µm.