Movie S2.

Movement of β-globin mRNA. HeLa cells were transfected with plasmids globin-BSL, globin-MSL, Bgl-YFP, and MS2-mKate (described in Figs. 1 and 2). Time-lapse images were acquired at 9.8 Hz with a 100-ms integration time by using TIRF microscopy. An LoG filter was applied to the images, and the movie is encoded at 10 Hz.