CCN1 and idiopathic pulmonary fibrosis: Its expression changes in response to endogenous factors and external stimuli, such as oxidative stress, mechanical stress, and ultraviolet irradiation [56,57,58,59], and aberrant CCN1 expression is associated with aging and age-related diseases, including idiopathic pulmonary fibrosis (IPF) [60] and OA [27,61,62].