them showed clear staining for βIII-tubulin in cortical neurons in the different layers (Figures 5D and 5E). Immunostaining for RanBP17 showed strong expression in layer II and III neurons of the young adult cortex, whereas it was often barely detectable above background in cortical neurons of old brains (Figures 5E and 5F). Quantification of neuronal RanBP17 immunofluorescence over background revealed significantly lower levels of RanBP17 in old brains compared to young (Figure 5G), and RanBP17 levels as determined by western blot analysis inversely correlated with age (Figures 5H and S4), thus confirming the decreasing expression RanBP17 protein with age in vivo. In addition, several independent “:omics” studies showed RanBP17 consistently among the very top age-dependent genes in 519 samples of glioblastoma multiforme (Broad Institute TCGA Genome Data Analysis Center, 2014), 480 samples of kidney renal clear cell carcinoma (Broad Institute TCGA Genome Data Analysis Center, 2013a), and 226 samples of thyroid adenocarcinoma (Broad Institute TCGA Genome Data Analysis Center, 2013b; summarized in Figure S5).
