Our IHC analysis of breast tumor specimens based on highly discriminating antibodies revealed an up-regulation of NME1 levels in carcinoma cells in DCIS tumors as compared to surrounding non-malignant tissues, whereas NME1 levels were significantly reduced in synchronous invasive tumor foci and in microinvasive carcinoma buds extending beyond the ruptured basement membrane. Here, NME1 is linked to ductal breast carcinoma in situ.