In order to study the regulation of lysyl oxydase (LO) in fibrosis, mRNAs were extracted from an enriched population of myofibroblasts (MF) isolated from liver of schistosomiasis infected mouse. Four mRNAs (5.5kb, 4.5kb, 2.4kb and 2.0kb) hybridizing with a LO cDNA probe were transcribed in fibrotic liver, but only the two largest mRNAs were found in MF. A cDNA library was constructed, allowing the cloning of twenty four cDNAs. The largest clone of 4689bp should correspond to the 5.5kb mRNA. Its sequence was essentially similar to the NIH-3T3 fibroblasts LO-ras recision gene (rrg4) cDNA, with the same exon/intron structure, but with some differences at the sites of initiation of transcription which were shown to occur mainly at -392 and -358 nucleotides before the putative start of translation. These two main sites of initiation did not explain the origin of the 4.5kb and 5.5kb mRNAs, and as no spliced variants were found among the 24 clones, some regulation should also involve the 3'end region.In order to study the regulation of lysyl oxydase (LO) in fibrosis, mRNAs were extracted from an enriched population of myofibroblasts (MF) isolated from liver of schistosomiasis infected mouse. Four mRNAs (5.5kb, 4.5kb, 2.4kb and 2.0kb) hybridizing with a LO cDNA probe were transcribed in fibrotic liver, but only the two largest mRNAs were found in MF. A cDNA library was constructed, allowing the cloning of twenty four cDNAs. The largest clone of 4689bp should correspond to the 5.5kb mRNA. Its sequence was essentially similar to the NIH-3T3 fibroblasts LO-ras recision gene (rrg4) cDNA, with the same exon/intron structure, but with some differences at the sites of initiation of transcription which were shown to occur mainly at -392 and -358 nucleotides before the putative start of translation. These two main sites of initiation did not explain the origin of the 4.5kb and 5.5kb mRNAs, and as no spliced variants were found among the 24 clones, some regulation should also involve the 3'end region.