Furthermore u-PA is potently upregulated by the proinflammatory cytokines TNF-α and IL-6 in a variety of human cancer cell lines in vitro and the u-PA system is significantly activated by infection and sepsis in vivo as evidenced by increased circulating levels of u-PA (Robbie et al, 2000; Abraham et al, 2003). This evidence concerns the gene IL6 and infection.