FRAP and FLIP are two techniques that are usually applied to study the dynamics of protein in living cells. In recent years, studies of protein dynamics by these two techniques showed: some proteins are mobile, and they rapidly associate and dissociate with their respective compartments in the nucleus of living cells. Furthermore, protein movement is mainly independent of energy, which indicates that proteins may use a passive mechanism of movement. Additionally, covalent modifications have effect on the mobility of some proteins. Protein dynamics in the karyon is important to the nuclear architecture and gene regulation, however, the detail mechanism is still unknown and expected to further study.