YY1 and pulmonary fibrosis: Also, YY1, which has been shown to repress p16 expression and curtail senescence in cancer cells, has also been associated with collagen production and implicated in fibrotic diseases such as idiopathic pulmonary fibrosis (IPF) and liver fibrosis through promoting myofibroblasts differentiation and increased collagen production by fibroblasts and myofibroblasts (68–71).