The protein, known as FRABIN is a specific regulator of CDC42 activity and it was postulated that the mutations led to loss of CDC42 activity, leading to reduced F-actin positive filipodia protrusions in cell cultural experiments. Whether CDC42 activity is compromised also in CMT4D, due to NDRG1 inactivation, is presently unknown, and might thus provide a starting-point for further studies into the molecular pathogenesis of CMT4D. Recently, cell death signals have been shown to induce trafficking of recycling endosomes through a pathway involving CDC42, and CDC42 was shown to be involved in FASenhanced membrane trafficking. Also, TP53 can induce apoptosis through death receptors by increased expression of FAS. NDRG2 silencing has been shown to inhibit TP53-mediated apoptosis, and inactivation of NDRG2 may elicit resistance against FAS-mediated cell death. Our microarray results may indicate an involvement of NDRG1 in trafficking of recycling endosomes. Additional research is required to explore if increased NDRG1 levels could result in TP53-mediated apoptosis through increased vesicle formation, internalization and recycling of FAS through activation of CDC42. Furthermore, the reported tumorpromoting role of NDRG1 and the role in metastasis suppression, which are R428 apparently contradictory may be explained by involvement of NDRG1 both in cell survival under hypoxia and in doxorubicin-induced apoptosis under normoxia. In summary, the pleotropic roles of NDRG1 reported in apoptosis, cell survival, myelin sheath maintenance and enhanced exocytosis in mast cells, and in the cellular responses to hypoxia, heavy metals, and androgenes may converge by NDRG1 influencing vesicular trafficking. Development of comprehensive therapy has reduced the mortality rate of breast cancer patients. However, regional and distant recurrences still threaten the lives of breast cancer patients. Despite the significance of proliferation of residual breast cancer cells, most prognostic factors measure demographic characteristics of the patient, tumor status or histological features. Interest in a prognostic factor that measures proliferative status of breast cancer and predicts response to therapy is high : the Ki-67 marker is a prominent candidate. Ki-67 protein is a cellular marker for proliferation. This nuclear protein is expressed in proliferating cells during G1 through M phases of the cell cycle, but is not detected in resting cells. The Ki-67 expression as detected by immunohistochemistry is one of the most reliable indicators of the proliferative status of cancer cells and is referred to as Ki-67 henceforward. In 2009, at the St-Gallen breast cancer conference, Ki-67 was recommended as a biomarker for prognosis and sensitivity of cancer cells to endocrine therapy or chemotherapy. In 2011, Ki-67 was regarded as one of the factors influencing molecular subtypes. Ki-67 expression is closely associated with the growth and invasion of breast cancer: Ki-67-positive breast cancers are more active in growth, more aggressive in invasion, and more metastatic.