FIG. 1.

VPA blocks chemotactic movement in wild-type Dictyostelium cells. (A) Quantification of speed for chemotaxing cells moving towards a source of cAMP in a pulsatile way, alternately increasing and decreasing speed. (B) Addition of VPA (1 mM) to cells (arrow) acutely blocks cell movement within 5 min. Three typical experiments are shown in panels A and B. See also the movie in Fig. S1 in the supplemental material.