28S RNA CISH Probe is recommended for the evaluation of RNA quality by chromogenic in situ hybridization (CISH). It is It is an oligonucleotide-based probe conjugated with fluorescein isothiocyanate (FITC) designed to bind to the 28S ribosomal RNA. The probe can be used on formalin-fixed, paraffin-embedded (FFPE) tissue specimens.