Characterization of FBG-325 and FBG-ΔAαC. FBG-325 was analyzed by SDS-PAGE under nonreducing (A) and reducing (B) conditions followed by Coomassie blue staining. The positions of migration of intact FBG (340 kDa), FBG-325 (325 kDa), and reduced FBG Aα, Bβ, BβΔ^1-42 , and γ chains are marked. ELISA (C) was performed using serial dilutions of MoAb 18C6 to detect the presence (FBG, □) or absence (FBG-325, •) of Bβ^1-21 . Western blot analysis using MoAbs against FPA, Aα^87-100 containing the RGDF^95-98 domain, and Aα^566-580 containing the RGDS^572-575 domain was performed on FBG and FBG-ΔAαC resolved under nonreducing (D) or reducing (E) conditions.