Genes induced during the G0/G1 transition in mouse fibroblasts.

Growth factors trigger a complex genetic response in quiescent fibroblast which involves approximately 100 genes. The genes so far identified encode for nuclear proteins, secretory molecules and components of the cytoskeleton and extracellular matrix. Ten of the nuclear proteins so far found can be grouped into families of transcription factors according to common structural components. These include the families of JUN, FOS, zinc finger proteins and nuclear hormonal receptors. Two of the secretory proteins share structural homology with cytokines and one of them has been shown to have a mitogenic capacity. These observations demonstrate that several of the immediate early genes encode for molecules which could regulate the expression of other genes whose products are essential for the progress through G1.