Transcription factor is a protein inside the cell regulating gene expression by binding to a specific DNA sequence. It’s involved in cell response to environmental stimulus such as chemicals, irradiation and stress. NF-κB protein family, which includes p50 and p65 proteins, are the most common ones found in almost all animal cell types. Their activities are essential in cancer mechanism and cell apoptosis. We’re interested in studying the distribution and transportation of p50 and p65, as well as how they respond to the stimulus in living cells, to further uncover their signaling pathways. We especially want to observe their activities in single molecular level by using our fluorescent microscopy and intracellular labeling technique.