XIST and breast cancer: XIST is a non-coding RNA gene located on the X chromosome with a length of 17kb, and is involved in the process of X chromosome inactivation.25 Either mutation or overexpression of XIST may lead to abnormalities in the non-activating processes of the X chromosome, which in turn may induce a range of diseases.24 For example, XIST has been identified to mediate tumor progression in colorectal cancer, breast cancer, ovarian cancer, and liver cancer.16,17,20,34 More fundamentally, Feng et al9 noted that XIST targeting miR-214-3p affects the growth of peri-implant ligament stem cells.