In ERα‐negative BC, we previously found snail family transcriptional repressor 2 (SNAI2), a zinc‐finger transcriptional factor, recruited lysine‐specific demethylase 1 to the promoter to transcriptionally suppress ERα expression by demethylating histone H3 lysine 4 dimethylation (H3K4me2). Here, SNAI2 is linked to breast cancer.