Fig. 3. Morphological changes in T lymphocytes migrating on ICAM1 (upper panel) and Matrigel (lower panel). (A) Cells were activated with PMA and incubated for 24 hours on immobilised ICAM1. Wild-type Jurkat T lymphocytes show no evident phenotypic changes whereas overexpression of cathepsin X in Jurkat T lymphocytes resulted in the development of extended uropods. White arrows indicate the uropods attached to ICAM1-coated surface and black arrows the uropods attached to other cells. (B) Wild-type Jurkat T lymphocytes remained in a spherical non-migratory state after 48 hours of incubation on Matrigel. Activation with PMA resulted in the development of cytoskeletal rearrangements in a small proportion of the wild-type cells. By contrast, in transfected cells cathepsin X induced the formation of a polarised phenotype with long uropods, independently of the activation with PMA. (C) In cathepsin-X-overexpressing cells the accumulation of GFP–-actinin-1 at the lamellipod (white arrows) is more evident than in wild-type cells. GFP–-actinin-1 is concentrated also at the adhesive tip of the uropod (black arrow) formed only in cathepsin-X-overexpressing cells. Scale bars, 100 µm (A,B) and 10 µm (C).