BAK1 and Behcet disease: To test the above hypothesis, we measured the protein levels of several pro- (Bax, Bad, Bak, Smac and active caspase-3) and anti-apoptotic factors (Bcl-xL, Bcl-xL/Bak dimer, survivin and Mcl-1), the mRNA and protein expression levels of mitochondrial fission/fusion proteins (Mfn2, Opa1 and Fis1), and the mitochondrial content in peripheral blood mononuclear cells (PBMCs) from BD patients and healthy controls.