Expression pattern of the main murine B" regulatory subunits in embryos. A murine embryo multiple tissue Northern Blot containing poly(A+) RNAs from murine embryos at days 7, 11, 15 and 17 (Clontech) was hybridised with isoform-specific RNA probes. Embryonic expression of mPR130/B"α1, mPR72/B"α2, mPR59/B"δ1, mPR59/B"δ2 and mG5PR/B"γ is shown. For quantification we used the ImageQuant program from Molecular Dynamics. Percentages of expression are relative to the most intense band of the murine tissues blot (Figure 6). This way, a comparison with the relative expression of a specific isoform in the different tissues (Figure 6) can be made. The β-actin control hybridisation is shown at the bottom and was used to correct for equal loading.