Although there have been several studies of the effects of forced over-expression of mutant SPOP protein in immortal cell lines [9–11], there appears to be no studies of endogenous SPOP mutations at the protein level in either primary prostate cancer cell lines or prostate cancer tissues, primarily due to the lack of antibodies capable of distinguishing between mutant and wild type SPOP protein. The gene discussed is SPOP; the disease is Familial prostate cancer.