Sustained supraphysiological activation of Notch signaling is associated with the development of osteoarthritis and the suppression of chondrogenesis, and the deletion of either Rbpj or the Notch target gene Hes1 prevents the osteoarthritis that follows the surgical destabilization of the medial meniscus (DMM) in mice (3, 4, 18, 19, 20, 21). This evidence concerns the gene HES1 and osteoarthritis.