BRD4 and osteoarthritis: In addition, the results from an increasing number of studies has shown that Brd4 is involved in the development of pulmonary fibrosis (Tian et al., 2016), cardiac hypertrophy (Spiltoir et al., 2013), osteoarthritis and intervertebral disk degeneration (An et al., 2018; Wang et al., 2019b).