Cos-1 cells transiently transfected with two chimeric proteins of a double mutant of Green Fluorescent Protein (GFP). Note the difference in staining between the upper and lower panels. The cells in the lower two images show nuclear exclusion of the GFP staining. Taken using 488 nm excitation and FITC filters. Dr. Jianzhong Zhang. Laboratory of Dr. Yoshinori Kowhi, University of California, Berkeley.