What is serum in cell culture?

Serum in cell culture is a complex mixture of proteins, growth factors, hormones, and nutrients that is added to cell culture media in order to support the growth and survival of cells in vitro. Serum provides a variety of essential components that support cell proliferation, differentiation, and metabolism, and can also modulate many key signaling pathways in cells. However, the use of serum in cell culture can also introduce variability and inconsistencies in experimental results, due to the variability of serum components from different sources and batches. Therefore, researchers may choose to use serum-free or defined media for certain applications or experiments.