PSEN1 and Alzheimer disease: Our findings of increased TfR1 expression in 5xFAD mice mimicking the advance stage of AD are not in agreement with the hypothesis of Lu et al. (2014), who suggested that TfR1 is upregulated at the early stage of AD as was shown in the cortex and hippocampus of APP/PS1 mice, and decrease with the AD progression [5, 24].