Specificity of anti-sperm-associated antigen (SPAG)5 antibodies. (A) Co-immunostaining of SPAG5 (green) and Usher syndrome 2A (USH2A; red) in retinal cryosections of adult (P20) rat using anti-USH2A and anti-SPAG5 antibodies. Both antibodies were blocked together with the SPAG5 antigen and after pre-absorption no specific SPAG5 signals were detected in contrast to the normal USH2A staining. (A') Western blot analysis of HA-tagged SPAG5 using (pre-absorbed) anti-hemagglutinin (HA) and anti-SPAG5 antibodies. After pre-absorption of the antibodies with the SPAG5 antigen, HA-SPAG5 could only be detected by anti-HA antibodies and not by the blocked anti-SPAG5 antibodies, indicating the specificity of the antibodies.