Fig. 1. Expression of CXCR4 and SDF-1 mRNA in postnatal mouse cerebella. (A) Northern blot analysis was performed on 20 µg total RNA isolated from pooled cerebella of litters taken at P3, P5, P7, P9 and P12. CXCR4 and SDF-1 mRNA were expressed at all ages. (B) Phosphoimager analysis was used to quantify the CXCR4/GAPDH and SDF-1/GAPDH mRNA signals for each sample. CXCR4 expression declined during the second postnatal week to approximately 30% of its P3 value. SDF-1 expression remained more constant over this time period.