DCLK1-IN-1 is a selective, oral bioavailability in vivo-compatible chemical probe of the doublecortin like kinase 1 (DCLK1 kinase) domain. DCLK1-IN-1 inhibits DCLK1 and DCLK2 kinases (IC50: DCLK1=9.5/57.2 nM and DCLK2=31/103 nM in binding and kinase assay, respectively) . DCLK1-IN-1 shows low toxicity, and can investigate DCLK1 biology and establish its role in cancer, like DCLK1+ pancreatic ductal adenocarcinoma (PDAC) [1].