PT-12, a putative Ras-activated proliferation-dependent gene, is expressedin patellar tendon and not in anterior cruciate ligament

We describe a gene (PT-12) that is expressed in the patellar tendon and not in the anterior cruciate ligament. We used a recently developed polymerase chain reaction-based subtractive cDNA analysis to discover genes that are overexpressed in the patellar tendon but not expressed in the anterior cruc iate ligament; the long-term objective was to find genes that are central t o the self-repair of the patellar tendon, in contrast with the inability of the anterior cruciate ligament to launch a repair response following injur y. PT-12 is a homologue of human S2 or mouse LLRep3 ribosomal genes, which are known to be overexpressed in highly proliferating cells. This study ope ns a new vista to the development of techniques and reagents to study the d ifferences between two periarticular tissues (i.e., the patellar tendon and anterior cruciate ligament) that differ primarily in their ability to self -repair.