A549 cells cultured in media conditioned by intact ECs, but not perlecan-silenced ECs, were less metastatic than control cells. (A) Increase in lung weights, relative to tumor-free animals, of A549 cells cultured for 4 days in unconditioned (control) media, media conditioned by intact ECs, and media conditioned by perlecan-silenced ECs (ECshPerl). (B) Metastatic index (see Materials and Methods) of lung cryosections in the above groups. *P < 0.05 versus control group by t test. Error bars show SEM.