The JARID1 (KDM5) family: There are four proteins named JARID1A, JARID1B, JARID1C, and JARID1D in the JARID1 (KDM5) family, which can demethylate methyl marks of H3K4.213,214 The structure of KDM5A contains three PHD domains, especially, the PHD1 domain in KDM5A can preferentially recognize unmethylated H3K4 histone tails and stimulate its activity (Fig. 5).215 It is worth noting that KDM5B is up-regulated in breast cancer and prostate cancer. The gene discussed is KDM5B; the disease is breast cancer.