RUNX2 and osteoarthritis: In addition, we saw the differential expression in the microarray data only, of the hedgehog target genes PITX1, MATN3, and RUNX2. Expression of transcription factor PITX1 has been shown during hind limb development in regions giving rise to cartilage joints, long bones and skeletal muscles, while its partial inactivation led to a progressive formation of osteoarthritis-like phenotype in aging Pitx1+/− mice [48].