Transcription factors on the move

We think of transcription factors as being confined to the cell where they are transcribed, but recent work shows they are able to move from cell to c ell in plants. plant cells are thought to communicate through membrane-line d channels called plasmodesmata. Although the size exclusion limit for thes e pores is small, microinjection experiments indicate that macromolecular t rafficking through plasmodesmata occurs and can be regulated. But can funct ional plant proteins in their normal expression domain also move between ce lls?A recent paper by Sessions et al. elegantly addresses this question usi ng meristem chimeras. Intriguingly, only one of the two proteins studied mo ved, thereby setting the stage for analysis of the mechanism and selectivit y of protein trafficking between cells.