However, the temporal window of ‘epigenetic memory’ reported in native chromatin contexts varies between different studies, from 5 to 10–15 days for both DNMT3A-CD (88,92,96,243) and KRAB (30,45,85,88,244) to up to 100 days in an inducible ZF-DNMT3A-CD system in breast cancer (81); at least 31 days employing 6ZFs-DNMT3A-CD targeting the MASPIN TSG promoter in breast cancer (80), or ∼168 days employing SadCas9-KRAB in the liver of adult mice (245). The gene discussed is SERPINB5; the disease is breast carcinoma.