Quantification of confocal image analysis was done by single cell identification using the image analysis software MetaMorph (Molecular Devices Co., Tokyo, Japan), and the relative fluorescence intensity of green, red, and yellow pixels was assessed. The relative fluorescence intensity of all individual colors was then expressed as percent of the total fluorescence intensity. p values were calculated by the Student's t test with two-tailed distribution and two-sample unequal variance parameters.