Primary aortic endothelial cells from transgenic mouse embedded in 3D collagen gels. Cell was fixed with 3% paraformaldehyde and stained with mouse antibody to phosphomyosin regulatory light chain (red), followed by anti-mouse Alexa 561 goat antibody and Alexa 488 phalloidin to stain for F-actin (green). Size and scale: 0.0789 micron/pixel, 1352x1040 pixels Images collected with a spinning disk confocal on a Nikon TE1000 with a 60X 1.2NA water objective using 300 ms exposure for the red channel and 200 ms for the green channel. See Fischer et al for details regarding preparation. http://www.ncbi.nlm.nih.gov/pubmed/19185493