U2OS osteosarcoma cells stained with fluorescein labeled antibodies to tubulin (left panel, green) and rhodamine-phalloidin which labels F-actin filaments or stress fibers (middle panel , red) and both overlaid (right panel).  Bar = 20µm.The image is courtesy of Yuhong Song, laboratory of Dr. David Chang, Dept. of Medicine, Hematology and Oncology, UCLA Medical School.