Chemotaxis: insights from the extending pseudopod

Chemotaxis is one of the most fascinating processes in cell biology. Shallow gradients of chemoattractant direct the movement of cells, and an intricate network of signalling pathways somehow instructs the movement apparatus to induce pseudopods in the direction of these gradients. Exciting new experiments have approached chemotaxis from the perspective of the extending pseudopod. These recent studies have revealed that, in the absence of external cues, cells use endogenous signals for the highly ordered extension of pseudopods, which appear mainly as alternating right and left splits. In addition, chemoattractants activate other signalling molecules that induce a positional bias of this basal system, such that the extending pseudopods are oriented towards the gradient. In this Commentary, I review the findings of these recent experiments, which together provide a new view of cell movement and chemotaxis.