Protein blot analysis of plasma PON1 and RBP1 levels from SAID discordant MZ twins and unrelated, matched controls. A. Representative protein blot analyses of the RBP1 (140 kDa), TF (77 kDa) and PON1 (43 kDa) proteins for each of the 10 SAID-discordant twin pairs (A, affected twin; U, unaffected twin) and unrelated, matched controls (C). B and C. Summary of replicate blot assays illustrating plasma PON1 (B) and RBP1 (C) protein levels among SAID-discordant twins and unrelated, matched controls. Data were normalized to the constitutively expressed transferrin protein (PON1/TF and RBP1/TF, respectively) and plotted to compare relative differences in PON1 or RBP1 protein levels among the three study groups (affected twin, unaffected twin, and unrelated, matched control).