Subsequent to TET1 gene expression, TET1 auto-demethylates its promoter and, subsequently, the demethylation of the promoter of homeobox A (HOXA) genes, HOXA7 and HOXA9, culminating in the effect from the TET1, HOXA7, and HOXA9 genes suppressing breast cancer invasion and metastasis [29]. Here, HOXA9 is linked to breast cancer.