Evaluate the role of cytokines in the JAK-STAT pathway.

• A. Cytokines inhibit the JAK-STAT pathway.
• B. Cytokines degrade the cytokine receptor.
• C. Cytokines act as ligands that initiate the JAK-STAT signaling pathway, regulating development and differentiation.
• D. Cytokines are transcription factors that directly regulate gene expression.

Answer: (C)