An Inhibitor Present in Calf Serum Which Prevents Growth of BHK21 Cells in Suspension Culture

Abstract

BHK21 cells do not form colonies in soft agar suspension culture in the presence of calf serum; but if swine serum is used instead they do so. In methylcellulose suspension culture supplemented with calf serum the cells synthesize very little RNA or DNA, but if swine serum is used there is a marked increase of syntheses. Calf serum was found to contain an inhibitor which prevents the induction, but not the continuation, of RNA and DNA synthesis in BHK21 cells. In contrast the growth of polyoma-virus-transformed cells is not affected by this serum inhibitor which has been partially purified from calf serum by ammonium sulphate precipitation followed by Sephadex G-200 column chromatography.