PARP1 and breast cancer: It has been demonstrated that Zeb1, Ezh2 and BMI1, master regulators of the EMT process and, consequently, of the acquisition of stemness traits, are also correlated with the hyperactivation of ATM, responsible for double-strand breaks repair, as well as the constitutive activation of CHK1 or PARP1, in cell cultures and mouse models of breast cancer [52], CSC derived from colorectal cancer patients [53], and other cancer types [43].