Development of fluorescent dual-FRET probe for simultaneous detection of caspase-8 and caspase-9 activities and their relative quantification

•The fluorescent sensor can distinguish activity of Casp8 and Casp9 presented solely or simultaneously in cell lysates.•Evaluation model allows also the relative ratio quantification of both caspases.•The fluorescent probe is accessible via a simple organic synthesis manner.•Application of the probe does not need any special instrumentation or techniques.•The probe is suitable for distinguishing of the extrinsic or intrinsic pathway of the apoptosis caused by various drugs treatment.