Fig. 2. PTP-PEST effect on motility depends on its catalytic activity. (A) Transient expression of GFP, PTP-PEST or PTP-PESTC231S in CHOK1 cells. Western blots for the KT3 epitope tag (KT3) or for GFP show expression levels of transfected proteins. (B) CHOK1 cells transfected with wild-type PTP-PEST, PTP-PESTC231S, or GFP were analyzed for their ability to migrate towards a FN substrate using a haptotactic migration assay. The lower membrane of a transwell chamber was coated with 10 µg/ml FN. While expression of a mock gene, GFP, did not affect CHOK1 migration, expression of wild-type PTP-PEST significantly impaired their migration. In contrast, expression of a catalytically inactive mutant, PTP-PESTC231S, did not inhibit CHOK1 migration, indicating that the catalytic function is critical for motility. The number of cells per field for five fields were scored in three separate experiments. Migration of transfected cells is expressed as a percentage of CHOK1 controls.

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