Movie S4.

Transfer of β-actin–MBS mRNA between donor and acceptor MEFs. Acceptor WT MEFs and donor β-actin–MBS MEFs expressing tdMCP–GFP (green) were cocultured for 24 h and then imaged were with a 150× objective, as detailed in Materials and Methods. Both cell types express TagRFP-T-ps (magenta). For this movie, cells were imaged at 10-s intervals, 11 z-sections of 0.6 µm each, for 45 min. Exposure time and laser power for each wavelength were 100 ms at 50% power for the 488-nm laser and 200 ms at 30% power for the 561-nm laser. The movie shows a maximum projection of each of 122 frames (elapsed time = 20 min, 10 s, starting from frame no. 1) at 5 fps. Note the presence of GFP-labeled β-actin–MBS spots in the mNT and possible retrograde transport back to the original donor cell (right).