TIMP1 and keloid: In contrast, other studies have demonstrated that the exogenous NO donor, DETA/NO (125–500 μM; t1/2 ~20 h), promoted TIMP-1, TGF-β1 and collagen synthesis in fibrosis-related disorders such as keloid (hypertrophic scar) and pulmonary fibrosis (Hsu et al., 2007).