Loss of myosin II isoforms induces morphological changes in 3D Cells were added to a collagen solution, poured into Teflon molds and allowed to incubate for 4 days.

<p>Constructs were washed, fixed, permeabilized, and stained with Phalloidin-TRITC and affinity purified myosin II antibodies. Cells were examined using Two Photon Microscopy. <b>(A-F)</b> Parental MDA-MB-231 cells in three dimensions had pyramidal cell bodies with multiple projections and significant staining of both IIA <b>(B)</b> and IIB <b>(E)</b> myosin isoforms, mainly diffuse throughout the cytosol. <b>(G-L)</b> IIA KD cells had rounded cell bodies with highly branched and elongated projections in all directions and very little residual myosin IIA <b>(H)</b> staining, mostly localized to the cell bodies. The IIB <b>(K)</b> in these cells remained diffuse throughout the cytosol. <b>(M-R)</b> IIB KD cells were elongated with fewer projections and tended to be localized to a single focal plane, with residual IIB <b>(O)</b> localized at cell edges and near the nucleus. For all cell types, myosin isoform localization in 3D was mainly cytosolic.