Western blots of Erb-B4. Overall, the bands corresponding to the holoprotein (~180 kDa) and ~60 kDa were decreased in all PSEN mutations as well as in the SAD cases relative to the ND controls. Of the degradation peptides that carry the Erb-B4 C-terminal epitope the most represented band, at ~55 kDa, demonstrated heterogeneous levels among different PSEN mutations. In the SAD cases the values were more similar to the control levels. The ~50 and ~30 kDa peptide bands also show large deviations among the PSEN, SAD and ND controls. The ~40 kDa band was increased in the ND controls when compared to the PSEN and SAD cases. SAD = sporadic Alzheimer's disease; ND = non-demented.