There are experimental data to support both of these suggestions.12 A recent study showed that interference with OCT4 binding in P19 embryonic carcinoma cells rendered the H19 allele partially resistant to demethylation, but also that when partially methylated, further methylation seeding (remethylation) could easily take place.13 Methylation seeding implies that inappropriate methyl groups recruit binding proteins that directly and indirectly promote both histone compaction and further DNA methylation. The gene discussed is POU5F1; the disease is embryonal carcinoma.