Growth factors (cytokines) are protein molecules that are involved in intercellular communication in the body and control important biological processes such as cell growth, differentiation, functional regulation, and immune response. These factors help cells receive specific signals and induce various physiological changes in response. Some of the main functions of growth factors (cytokines) are listed below:

1. Cell proliferation: Growth factors signal cells to promote proliferation and support the formation of new cells, which is important for tissue repair and regeneration.
2. Cell differentiation: Growth factors provide signals to induce differentiation of undifferentiated cells into specific cell types, which contribute to the formation of specific tissues and organs.
3. Immune response: Cytokines play a key role in regulating the immune system, controlling communication between immune cells and inflammatory responses.
4. Cell motility: Growth factors regulate cell motility, providing signals for cells to move in specific directions, which is relevant in embryology and tissue regeneration.
5. Cell survival and apoptosis (cell death): Growth factors signal cells to promote their survival, but they can also induce programmed cell death (apoptosis) of unwanted cells.
6. Angiogenesis: Growth factors are involved in angiogenesis (blood vessel formation), improving the supply of oxygen and nutrients to tissues.
7. Cell-cell interactions: Growth factors contribute to the development and maintenance of multicellular organisms through cell-cell interactions.

Aberrant growth factor activity and regulation can contribute to the development of cancer and other diseases, making precise regulation and control of growth factors crucial for healthy physiological processes.