<p>It is intended to provide a method of acquiring a gene inhibiting cartilage differentiation which comprises forcibly expressing a transcriptional factor in a cell lacking the transcriptional factor (preferably forcibly expressing Runx2/Cbfa1 in a chondrocyte lacking Runx2/Cbfa1), and acquiring a gene the expression of which is thus induced by the DNA chip method, the subtraction method or the like; and a chondrocyte lacking Runx2/Cbfa1 which is needed in performing the above method. It is also intended to provide a polynucleotide obtained by the above method; a polypeptide encoded by the polynucleotide; an antibody against the polypeptide; a recombinant vector containing the polynucleotide; a transformant having the recombinant DNA vector; a cell expressing the polypeptide; a transgenic animal having the polynucleotide; a model animal of bone and/or joint diseases (preferably arthritis derformans); a method of screening a remedy and/or a preventive for bone and/or joint diseases (preferably arthritis derformans) by using the above susbtance(s); a candidate compound for a remedy and/or a preventive selected by this method; and a medicinal composition and a diagnostic method for bone and/or joint diseases (preferably arthritis derformans).</p>
