In Vitro: DDR1-IN-1 effectively blocks collagen-induced DDR1 pY513 autophosphorylation in U2OS cells (EC50 = 86.76 nM) with excellent selectivity over a panel of >380 kinases. DDR1-IN-1 inhibits DDR2-mediated MT1-MMP activation in human rheumatoid synovial fibroblasts (RASF) upon collagen stimulation (IC50 < 2.5 μM) and enhances PI3K/mTOR inhibitor GSK2126458 antiproliferation efficacy in SNU-1040 colorectal cancer culture.