PRG3 is mainly expressed in the brain and expression decreases during maturation. (A) Quantitative real-time PCR of different mouse tissues (age P5) revealed the most prominent PRG3 mRNA expression in the brain. Data were normalized to β-actin. (B) Western blot analysis of protein lysates from various mouse tissues (age P5) shows a solitary signal in brain lysates (probed with anti-PRG3 53 antibody). No protein was detected in lysates from other tissues (top). As loading control β-actin was used (bottom). (C) Quantitative real-time PCR of mouse hippocampal tissue between E16 and P30 revealed age-dependent changes in expression levels. The highest PRG3 mRNA expression was detected around birth with a decline in expression levels until adulthood. Data were normalized to HPRT. (D) Western blot from total protein lysates of mouse hippocampal tissue between E16 and P60 (anti-PRG3 53 antibody). A signal was detected from E16 onwards with the strongest signal found around P5. From P10 to P20 a decrease in signal intensity appeared and after P20 the signal was hardly detectable (top). Anti-β-actin was used as loading control (bottom).