Western blot analysis of the culture medium and CHO cell lysate. Samples of medium (5 μL) were subjected to 8% SDS-PAGE under nonreducing conditions (A) or 10% SDS-PAGE under reducing conditions (B). The blots were developed with a polyclonal antibody to fibrinogen and reactive bands were detected by chemiluminescence, as described in “Materials and methods.” Purified plasma fibrinogen (3 ng) was electrophoresed in the lanes labeled S; medium from individual CHO lines was electrophoresed in the lanes labeled: I, γ387I; R, γ387R; L, γ387L; M, γ387M; A, γ387A. Samples of cell lysate (10 μL) were subjected to 8% SDS-PAGE under nonreducing conditions (C) or 10% SDS-PAGE under reducing conditions (D). Blots were developed as described. Bars at 340 kDa, 290 kDa, and 155kDa, and at 67 kDa, 56 kDa, and 47 kDa, indicate intact fibrinogen, intermediate complex (Int), and AαBβγ-complex (AαBβγ) in panels A and C, or the normal Aα-, Bβ-, and γ-chains in panels B-D.