Issues

Cover picture: Immunofluorescent images of cells from an NIH-3T3 line that express a constitutively active form of Pak1 (Pak1^E423) in a tetracycline-dependent manner are shown. The left image is composed of cells grown in the presence of tetracycline (F-actin, green; vinculin, red) and appear identical to the parental, nontransfected cells. The cell on the right was grown in the absence of tetracycline and expresses a high level of Pak1^E423 (blue), resulting in the formation of a single, asymmetric lamellipodia characteristic of a motile fibroblast. See related article in this issue by Sells et al., 837–849.