Zmp is implicated in SDC-1 ectodomain cleavage. The concentration of SDC-1-cleaved ectodomains in NMuMG cell culture medium was measured after treatment with 100 µg of Zmp protein, 10X concentrated supernatants of either S. suis wild-type P1/7 (WT), S. suis Δzmp (supplemented or not with 100 µg of recombinant Zmp) or S. suis compΔzmp. Samples were blotted on Immobilon Ny+ and incubated with anti-mouse SDC-1 (281-2) antibodies. The capacity of the Δzmp mutant to cleave SDC-1 ectodomains was significantly reduced in comparison to the WT strain, while the complementation of zmp gene restored WT phenotype. Recombinant Zmp protein also cleaved SDC-1 ectodomains. This activity was amplified when Zmp protein was incubated with zmp-deficient mutant culture supernatant. The concentration of shed SDC-1 ectodomains was determined using SDC-1 ectodomains purified from NMuMG cells as standards, as previously described . Data represent the mean ± SEM from at least three independent experiments. *(p < 0.05) indicates a significant difference between treated groups and the medium; #(p < 0.05) between treated groups.