s 4 A Figure 4-13 Distribution of actin in a cultured fibroblast A Figure 4-14 Fluorescence inicrogral aph of che endoplasmic cell. A fixed human skin fibroblast was permeabilized with a reticulum(ER)in a flattened rcgion of a living monkey kid- detergent and stained with a fluorescene antiactin antibody. ney epithelial cell, The ER is a set of membrane fibers that fibers within it. Courtesy of E. Lazarides. eat larger, nonreticular fluorescent structures are mitochon o This fluorescence micrograph of a cell shows the long actin fuse with each other to form a network, or reticulum. The dria(M).[Scc C. Lee and L. B. Chen, 1988. Cel! 44: 37-46. Courtesy of L. B. Clen. ouiat2i788-1r dunhe tin