Decoy proteins induce biallelic expression of H19 in MCF7 but not in HBF1 or WSF7 cells. (A–D) The two parental alleles of H19 were distinguished by polymorphic restriction enzyme Rsa1. Note the biallelic expression of H19 in MCF7 clones but monoallelic expression of H19 in HBF1 and WSF7 clones. (B and D) Allelic expression of H19 in MCF7 (B) and fibroblast WSF7 cells (D) that are stably transfected with ZF-EGFP decoy protein construct. Control, untreated cells; mock, virus carrying the empty vector.