The actin system is involved in different cellular processes such as exo- and endocytosis, organelle motions, maintenance of organelle distribution, motility, cell division, and cytoplasmic streaming in plant cells. Several substances are known to influence these processes by altering intracellular actin organization and have been used extensively for cell biological research. Their mechanisms of action are mostly destructive on actin filaments (F-actin), either by inhibition of F-actin elongation as in the case of cytochalasins (1 ) or by interaction with actin monomers (G-actin) in order to avoid actin polymerization as described for latrunculins (2 ). In contrast, F-actin polymerizing and stabilizing capacities were found for jasplakinolide (3 –6 ). Moreover jasplakinolide has the valuable advantage of being membrane permeable (7 ).