DDR1-IN-1 is a potent and selective inhibitor of discoidin domain receptor 1 (DDR1), a collagen-activated receptor tyrosine kinase. It is primarily used in research settings to study the role of DDR1 in various cellular processes, particularly those related to fibrosis, cancer progression, and tissue remodeling. By inhibiting DDR1 activation, DDR1-IN-1 helps block downstream signaling pathways involved in cell migration, proliferation, and extracellular matrix deposition. In cancer research, DDR1-IN-1 has been applied to investigate tumor-stroma interactions, especially in carcinomas where DDR1 signaling contributes to tumor growth and metastasis. It has shown utility in models of breast, ovarian, and lung cancers, helping to dissect how collagen signaling through DDR1 supports tumor survival and resistance to therapy. Additionally, DDR1-IN-1 is used in fibrosis studies, including kidney and liver fibrosis, where DDR1 activation promotes fibroblast activation and collagen accumulation. Its application allows researchers to assess the therapeutic potential of targeting DDR1 in chronic fibrotic diseases. Due to its selectivity and cellular activity, DDR1-IN-1 serves as a valuable pharmacological tool for validating DDR1 as a therapeutic target and for guiding the development of new drugs aimed at DDR1-related pathologies.