A, schematic representation of the experimental setup (green, p35S; blue, p40S). B, SPR ligand capture experiment showing the p40S-to-p35S subunit interaction in a 1-to-1 binding mode. Step 1, immobilization of F8-p35S-F8 on EDA-coated chip. Step 2, injection of p40S-KSF/KSF-p40S or KSF-TNF (negative control). RU, resonance units. C, kinetic data after blank subtraction and curve fitting (black curves). Experiments were analyzed in triplicates.