A basic research subject is the study on interactions between proteins, DNA and RNA. Majority of DNA and RNA-binding proteins are self polymerization-prone and may form aggregates that are difficult to bind DNA or RNA, thus hampering experiments. Labeling the proteins with fluorescein isothiocyanate significantly inhibits this tendency and markedly increases the binding efficiency of these proteins to bind nucleic acid molecules. This simple method has been utilized in the investigation on binding of C/EBPβ 3′UTR RNA by cytokeratin 18.