It has been observed experimentally that single serum treatment instigates Hes1 mRNA oscillation with 2–3 hour cycle in various cultured cells like fibroblasts (C3H10T1/2), myoblasts (C2C12), neuroblastoma cells (PC12) and teratocarcinoma cells (F9) and there exists a time delay of the order of 15–30 minutes between Hes1 protein and Hes1 mRNA oscillations27. This evidence concerns the gene HES1 and teratocarcinoma.