DPP4 and neoplasm: The new probe has been used forimaging DPP IV in human plasma, living Caco-2 colorectal cancer cells,tumor-bearing pancreatic tissue, and zebrafish embryos and larvae.The probe response is reached by the assembly of an enzyme-recognizinggroup (Gly-Pro) on the TP fluorophore (dicyanomethylene-4H-pyran derivative, DCM-NH2), forming an enzyme-sensitivedonor–acceptor (D–A) system showing high ratiometricfluorescence output.