Fig. 1 Cytotoxicity of SEPEC cytotoxic factor on HUVEC. (A) HUVEC Cell Control, (B) HUVEC treated with  E. coli  K12 C600 culture supernatant, (C) HUVEC treated with chromatographic fractions (Superose 12 10/300GL), (D) HUVEC treated with SEPEC 15 culture supernatant. After treatment, all cells were incubated for 24 h. Magnification for all images: 200×. Electrophoretic profile of purified cytotoxic factor in (E) native PAGE showing a single protein band and (F) SDS-PAGE showing two protein bands with molecular masses between 70 and 100 kDa. **Active fractions obtained by gel filtration on Superose 12 10/300GL were run in both cases. *M – molecular mass markers.