The use of His-tags and GFP-tags in molecular biology research had significant contributions and led to many discoveries. For example, a study was performed to investigate whether the interaction of two cellular proteins called Nubp2 and Nubp1 is important for their functions (Okuno et. al., 2010). Both of Nubp2 and Nubp1 were GFP-tagged; however, some were GFP-tagged at C-terminus and others were GPF-tagged at N-terminus (Okuno et. al., 2010). Therefore, the localization of proteins can be monitored within cells through fluorescence (Okuno et. al., 2010). The obtained results indicated that the C-terminal domain of Nubp1 is responsible for the regulation of localization, and that both termini of Nubp2 are responsible for nuclear transfer and nuclear morphology it.