Western blot analysis of BDNF expression in human serum (A) and human brain (B). Polyclonal rabbit BDNF antibody to BDNF (129-138; here whole serum antibody R-083-100 at 1:1000 dilution is shown) detects monomeric BDNF at 14 kDa in both samples, as well as monomeric proBDNF at 32 kDa in human brain (B). In addition, a 18 kDa BDNF isoform is detected in human serum (A), confirmed with a monoclonal mouse antibody to rhBDNF, Clone 4C8 (M-1744-50/100, 1 µg/mL). A 18 kDa BDNF-isoform has previously been detected with other BDNF antibodies ( Tongiorgi et al., 2012 ; Silhol et al., 2007 ). In human brain (B), a 28 kDa band is prominent which might relate to BDNF dimer or truncated BDNF isoform ( Tongiorgi et al., 2012 ). Western Blotting Method: SDS-PAGE: denaturing and reducing, 12% Bis-Tris gel; Transfer: Tris-Glycine buffer, semi-dry transfer; Membrane: nitrocellulose (0.22 µm); Blocking: 5% skim milk in TBST, 1 hour at RT; Primary antibody: overnight at 4°C; Secondary antibody: anti-mouse-HRP or anti-rabbit-HRP (1/6000), 2 hours at RT; Detection: Chemiluminiscence.