BINDING OF NUCLEAR PROTEINS TO THE C-FOS PROMOTER REGION--464 -435 CORRELATES WITH CELL-PROLIFERATION/

Binding of nuclear proteins to the mouse c-fos promoter region of 30 b p (nucleotides -464/-435 relative to TATA box) upstream of the PDGF-re sponsive element was studied by gel retardation assay. One or several factors present in nuclear extracts from various mouse and human cell lines was found to bind to this promoter region Analysis of DNA-protei n complexes from nuclear extracts of quiescent cells or those stimulat ed with 20% fetal calf serum revealed only one retarded band, while in the case of extracts from actively proliferating pseudonormal or tumo rigenic cells an additional retarded band with higher mobility in PAG was observed. The molecular masses of both factors interacting with th e c-fos promoter region determined by affinity modification were 59 kD a It is proposed that these factors are modified forms of the same pro tein.