Overlap of differentially expressed transcripts and proteins revealed CRABP1 up-regulation specific for an increased Aβ
ratio. Comparison of C99I45F or C99V50F versus C99WT revealed differentially expressed transcripts, of which each of the 60 most up-regulated were used here. The 20 most up-regulated proteins each were selected for the corresponding proteomic approach. An intersection of the transcriptomic and proteomic data was subsequently performed. Only the intersection of both approaches (four transcripts and proteins) was used for further analysis. Out of these four, only CRABP1 was up-regulated in C99I45F, whereas no differential expression was found in C99V50F (both mutants compared to C99WT). The remaining three transcripts and proteins were differentially expressed in both mutants. The proteomic approach was performed blinded by an independent laboratory. The term 'differentially expressed' was applied when the fold change exceeded a threshold of at least 1.9 either on the transcript or protein level.