Western blot analysis of the culture medium.

Samples of medium (5 μL) were subjected to 8% SDS-PAGE under nonreduced conditions (A) or 10% SDS-PAGE under reduced conditions (B). The blots were developed with a polyclonal antibody to fibrinogen and cross-reacting bands detected by chemiluminescence, as described in “Materials and methods.” Plasma fibrinogen (3 ng) was run in lanes labeled Fbg; medium from individual CHO lines were in lanes labeled 379: γ379-1; 384: γ384-33; 385: γ385-24; 386: from left to right, γ386-20, -37, and -39; 411: γ411-31; αβ: AαBβ-CHO cells; 387: γ387-5; 390: γ390-16; 395: γ395-2: 401: γ401-25; 406: γ406-7. Arrows at 340 kd, or 67 kd, 56 kd, and 47 kd indicate intact fibrinogen (A) or the normal Aα, Bβ, and γ chains (B). Arrows labeled γ387 and γ411 indicate this truncated and normal γ chain, respectively (B).