A 42-year-old woman presents with progressive central obesity, facial plethora, and proximal muscle weakness over 18 months. On examination, the structure marked **D** in the diagram is noted—broad, purple striae measuring 1.5 cm in width over the abdomen and axillae. Her blood pressure is 158/94 mmHg, and fasting glucose is 142 mg/dL. Which of the following best explains the pathophysiology of the finding marked **D**?