Cytokines are a broad category of proteins responsible for sending signals to the molecules that aid cell to cell communication in immune responses and thus stimulate the movement of cells towards sites of inflammation, infection and trauma. Cells upon activation further produce more cytokines.

Chemokines are signaling proteins with ability to induce directed chemotaxis in nearby responsive cells.

Growth Factors are generally considered as a subset of cytokines, refer to the diffusible signaling proteins that stimulate cell growth, differentiation, survival, inflammation, and tissue repair. They can be secreted by neighboring cells, distant tissues and glands.