Figure 1.

LOX isoform is expressed in multiple forms. A, human lung fibroblasts and bovine vascular endothelial cells were incubated for 4 days under basal conditions or in the presence of 5 ng/ml TGF-β1. Then, cell supernatants were taken and concentrated using a 10-kDa cutoff centrifugal filter. An aliquot was fractioned by SDS-PAGE and assayed by immunoblotting with a specific LOX antibody recognizing the C-terminal catalytic domain. Multiple immunoreactive bands were observed with molecular masses ranging from 25 to 30 kDa. B, generation of HEK293 cells overexpressing human LOX in a tetracycline inducible manner. LOX protein in the total cell extract and in the supernatant was assessed by immunoblotting under basal conditions and upon induction with the tetracycline analog, Dox. The precursor form at 50 kDa and multiple shorter forms (at 25–30 kDa) are identified in the culture medium of Dox-treated cells. The blots shown correspond to representative experiments performed twice with two independent preparations.