The mechanism by which testosterone alters cell function is by:

• A. Binding a receptor tyrosine kinase on the cell surface to trigger a MAPK phosphorylation cascade without directly altering transcription
• B. Diffusing through the plasma membrane and binding an intracellular androgen receptor that acts as a transcription factor to regulate gene expression
• C. Binding a cell-surface receptor that activates adenylate cyclase to increase cAMP and rapidly phosphorylate target proteins
• D. Stimulating nitric oxide synthase to generate nitric oxide that activates soluble guanylyl cyclase and increases cGMP

Answer: (B)