Fig. 6. A productive paxillin–PTP-PEST interaction is required for PTP-PEST-regulated cell migration. Modified Boyden chamber assays were performed as described in Materials and Methods to determine whether the paxillin–PTP-PEST interaction was important for the regulation of cell migration. PTP-PEST^–/– cells were transiently transfected with GFP alone or with PTP-PEST, PTP-PEST and paxillin, or PTP-PEST and paxillin C523S. PTP-PEST^–/– cells exhibit reduced migration rates compared with PTP-PEST^+/– cells. This defect was partially rescued by overexpression of PTP-PEST. However, this rescue was completely abolished when PTP-PEST was co-expressed with the paxillin C523S mutant. Results show the mean±s.d. and represent three independent experiments. **P<0.001.