p53 homologue p63 encodes for different isotypes able to either transactivate p53 reporter genes (TAp63) or act as p53-dominant-negatives. p63 is detected in prostatic basal cells in normal prostate; however, it is negative in malignant tumors of the prostate gland. Thus p63 antibody may be a valuable tool in the differential diagnosis of benign and malignant tumors of prostate gland and can be used in a panel of antibodies such as HMW CK [34ßE12], PSA and PSAP. p63 may play a significant role in prostate development by maintaining a prostate stem cell population. Striated muscle staining may be observed with p63.