Movie S5.

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 2.5 h and then were imaged 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 10 min. Exposure time and laser power for each wavelength were 600 ms at 55% power for the 488-nm laser and 400 ms at 35% power for the 561-nm laser. The movie shows maximum projection of each of seven frames (frames 48–54) at 1 fps. (Scale bar: 5 µm.) Note the apparent transfer of a GFP-labeled β-actin–MBS spot from the lower cell via the mNT and its appearance in the cytoplasm of the upper acceptor cell.