Fig. 9. Potential role of cathepsin X in the aggregation, migration and invasiveness of T lymphocytes. The potential physiological role of cathepsin X was investigated by its overexpression in T lymphocytes. Overexpressed cathepsin X induces morphological changes and promotes migration, invasiveness and homotypic aggregation by modulating the activity of the β2 integrin LFA-1 that is abundantly expressed in T lymphocytes.