The sound of one foot walking

Cells often extend pseudopodia to migrate, but it has been difficult to characterize this process biochemically because intact pseudopodia could not be isolated from cell bodies. Now, on page 725, Cho and Klemke describe a clever method for purifying pseudopodia that have been induced to grow or retract, and identify a signaling complex whose assembly and disassembly controls these processes.

Using a chemoattractant, the authors induced cultured mammalian cells to extend pseudopodia through 3.0-μm pores in a membrane. Under these conditions, over 90% of the cells extend a single leading pseudopodium, allowing Cho and Klemke to scrape away the cell bodies and extract the remaining pseudopodia with detergent. Because removal of the chemoattractant causes the pseudopodia to begin retracting, the system permits the purification of either growing or retracting pseudopodia for direct comparisons.

Analysis of the purified...