This antibody recognizes a protein of 110 kDa, which is identified as androgen receptor (AR). It reacts with full length, and the newly described A form of the receptor. It does not cross react with estrogen, progesterone, or glucocorticoid receptors. AR functions as a steroid-hormone activated transcription factor. Upon binding the hormone ligand, the receptor dissociates from accessory proteins, translocates into the nucleus, dimerizes, and then stimulates transcription of androgen responsive genes. The expression of AR is reportedly inversely correlated with histologic grade; ie, well differentiated prostate tumors show higher expression than the poorly differentiated tumors. In prostate cancer, AR has been proposed as a marker of hormone-responsiveness and thus it may be useful in identifying patients likely to benefit from anti-androgen therapy. Anti-androgen receptor has been useful clinically in differentiating morpheaform basal cell carcinoma (mBCC) from desmoplastic