Which sequence of events best describes how a signal transduction pathway can lead to changes in gene expression?

• A. Ligand binding -> Transcription factor activation -> Receptor activation -> Second messenger activation -> Gene expression change
• B. Second messenger activation -> Ligand binding -> Receptor activation -> Transcription factor activation -> Gene expression change
• C. Receptor activation -> Ligand binding -> Second messenger activation -> Transcription factor activation -> Gene expression change
• D. Ligand binding -> Receptor activation -> Second messenger activation -> Transcription factor activation -> Gene expression change

Answer: (D)