The presence of hypoxic areas is common in all breast lesions but no data clearly correlate low oxygenation with the acquisition of malignant features by non-invasive cells, particularly by cells from ductal carcinoma in situ (DCIS), the most frequently diagnosed tumor in women. | Protective role of all-trans retinoic acid ATRA against hypoxia-induced malignant potential of non-invasive breast tumor derived cells