Susceptibility of A549 lung cell-derived FBG to thrombin and plasmin cleavage. (A) Metabolically labeled FBG in A549 conditioned media was untreated (lane 1) or treated with thrombin (lane 2) and immunopurified and the resulting fibrin(ogen) Aα/α, Bβ/β, and γ chains were reduced then resolved on 7% polyacrylamide gels. (B) The untreated (lane 1) and plasmin-treated (lane 2) samples were resolved nonreduced on 8% polyacrylamide gels. The molecular weight markers (lane M_r ) in (B) are, from top to bottom, 200, 97, 68, and 46 kD. Intact FBG (340 kD) is denoted by the arrow.