Statistical analysis of electron miscroscopy data was analyzed using the Mann-Whitney test (independent samples and two-sided; GraphPad). Statistical analysis of immunoblotting, PCR, and fluorescence-activated cell sorting (FACS) data were performed using unpaired, two-tailed Student’s t test (Excel software). Values are shown as means ± SD of at least three independent experiments. P values <0.05 were marked by an asterisk. Densitometric analysis of immunoblots was performed using the Adobe Photoshop software. The control ratio was arbitrarily defined as 1.00. Normal distribution was assumed on the basis of the appearance of the data, since n < 5. No statistical method was used to predetermine sample size for animal studies. The animal experiments were not randomized. The investigators were not blinded to allocation during experiments and outcome assessment. No exclusion criteria were applied to exclude samples or animals from analysis.