Fig. 4. Ext1 and Ext2 expression increases during postnatal cerebellar development. (A) Northern blot analysis of Ext2 expression in developing and adult mouse cerebellum reveals that expression increases with increasing postnatal age, particularly from P4 to P9. Ext2 mRNA is present as two transcripts of 3.5 and 4 kb. (B) Ext1 expression demonstrates a similar increase between P4 and P9. Ext1 mRNA is present as a single species of 2.7 kb. Ethidium Bromide images corresponding to each northern blot are shown as loading controls (numbers refer to postnatal age; A, adult).