Biosynthesis and Secretion of Factor VII, Protein C, Protein 5, and the Protein C Inhibitor From a Human Hepatoma Cell Line

Using specific radioimmunoassays. 8 day cultures of Hep G2 cells were shown to contain in their supernatants 16, 74, and 828 ng/mL and in their cell lysates, 8, 55, and 48 ng/2 x i0 cells of factor VII, protein C. and protein S. respectively. These proteins and the protein C inhibitor were functionally active. and each of these activities was neutralized by their respective polyclonal antibodies. Although vitamin K had a modest effect, warfarin decreased the activity of secreted factor VII, protein C, and protein S by 50% to 90%. Protein C and protein S antigens were reduced threeto fourfold by warfarin. The protein C inhibitor antigen and activity were unaffected by vitamin K or warfarin treatment. Intrinsic labeling and immunopre-