Finally, to confirm the correlation between L1 demethylation and the expression observed in BC cells, we assessed L1-promoter methylation in a subset of 41 BCs, balanced for the PAM50 molecular subtypes (Luminal A: n = 8, Luminal B: n = 11, basal-like: n = 12, and HER2-enriched: n = 10). The gene discussed is ERBB2; the disease is breast cancer.