Expression of YB-1 in normal breast tissue, non-invasive and invasive breast cancer. (A) Only weak cytoplasmic YB-1 staining is detectable in normal breast tissue. (B) Scale-up of specimen shown in A. The magnification demonstrates weak YB-1 expression in luminal-epithelial breast cells. (C) Moderate YB-1 expression in a ductal carcinoma in situ (DCIS) of the breast. (D) Scale-up of specimen shown in C. (E) Invasive ductal breast cancer with abundant nuclear YB-1 expression. (F) Scale-up of specimen shown in E. Magnifications: A, C, E: 100×; B, D, F: 400×.