The tumor and tissue uptake and ratios for the two xenograft types LNCaP and 22RV1, with 22RV1 being a cell line with lower basal expression of fPSA, were similar and in well agreement with previous results with 89Zr-labled 5A10 in 22Rv1 and LNCaP-AR xenografts [8]. The gene discussed is AR; the disease is neoplasm.