Fig. 1. Processing of collagen type XVIII by MMPs and cysteine-type cathepsins. SFCM from EOMA cell cultures was collected after 48 h incubation in the presence of increasing amounts of various class-specific protease inhibitors. A 0.5 ml aliquot of SFCM was concentrated, separated on 7.5–17.5% polyacrylamide–SDS gradient gels and electroblotted onto nitrocellulose. Collagen XVIII fragments containing endostatin were detected with a polyclonal antibody against human recombinant endostatin. For comparison, recombinant murine endostatin (ES) and murine NC1 were loaded onto the gels in (A), (D) and (H) on the right and left sides of the gels, respectively.