Despite significant upregulation in Grb2 transcript levels detected using qRT-PCR [Fig. 2A(iii)], in the presence of both the AD-inducing factors (AICD and Aβ), the expression of Grb2 protein was, however, higher in comparison to that upon treatment with AICD or Aβ alone [Fig. 2A(i),A(ii)] as western blotting demonstrated that AICD and Aβ were unable to increase Grb2 protein levels individually. This evidence concerns the gene GRB2 and Alzheimer disease.