Comparison of immunostaining intensities (measured as average optical density ± SD) in Western blot analysis of bening breast lesions, in situ and infiltrating breast cancer. The labeled cells are classified in three groups according to their intensity range: low (< 10), intermediate (between 10 and 15) and high (>20). For each protein, values with different superscript letter differ significantly (P ≤ 0.05) between them. Those values sharing the same superscript are not statistically different from each other. Statistical analysis refers to each antibody separately. The mean values and SD for each group have been calculated from all samples corresponding to the group.