Fig. 5. Summary of results. In –(M)/+ fetuses (middle), the maternal (ChßGI)2 acts as a chromatin insulator, substituting for this property of the maternal ICR in +/+ fetuses. Allele-specific expression of Igf2 and H19 was unaffected. In +/–(P) fetuses (bottom) the paternal (ChßGI)2 acted as a chromatin insulator as did the maternal (ChßGI)2. Consequently both Igf2 alleles were strongly repressed and total Igf2 RNA was very low. Both H19 promoters had access to the enhancers in cis, and H19 was expressed biallelically. Other details are as described in the legend to Fig. 1.