AR and prostate cancer: However, the AR is expressed throughout the progression of prostate cancer, including >80% of hormone refractory tumors, suggesting that AR signaling remains essential.[10, 11] It has also been shown that over-expression of the AR alone is sufficient to promote hormone refractory disease.[12] Indeed, the persistence of AR in the metastatic LNCaP cell line and continued nuclear expression of hormone refractory tumor samples is indicative of continued AR involvement.[13]