To demonstrate the physiological significance of RNF144A regulation of PARP1, we next analyzed the expression levels of endogenous RNF144A and PARP1 proteins in an isogenic breast cancer progression model system, including parental MDA-MB-231 and its two highly metastatic variants LM2-4173 and LM2-4175 [38]. Here, RNF144A is linked to breast cancer.