Serum response factor (SRF) is a widely expressed transcription factor involved in the expression of genes linked to cellular growth and muscle differentiation. Its target genes include cellular immediate early genes such as c-fos and structural cytoskeletal proteins, such as actins, myosins, tropomyosin, and vinculin. Serum-induced transcriptional activation of immediate early genes involves the formation of a ternary complex of SRF with a 62 kDa ternary complex factor (TCF) which binds to the serum response element (SRE). SRF is also involved in vascular smooth muscle differentiation by regulating the expression of several contractile and cytoskeletal genes. It is widely accepted that normal smooth muscle cells are subverted to one of growth and excess matrix production in various disease.
Cells will undergo genotypic changes resulting in reduced responsiveness over time in normal cell culture conditions. Genetic instability is a biological phenomenon that occurs in all stably transfected cells. Therefore, it is critical to prepare an adequate number of frozen stocks at early passages.