A 58-year-old man presents to the emergency depament with severe back pain. His history is negative for trauma and he has no other complaints. He denies urinary frequency, hesitancy, or dysuria. A digital rectal examination confirms the presence of a firm, hard, asymmetrical and stony prostate, suggestive of prostatic malignancy. In addition to PSA, which of the following markers can be demonstrated in the tumour cells?