Fig. 4. Immunohistochemistry shows that axonal guidance signaling-related proteins are down-regulated in the cortex of postmortem brain in CTE patients. (A) The immunoreactivity of TUBB3 protein was down-regulated in both the grey matter and the white matter of the cortex in CTE postmortem brain compared to normal control. TUBB3 was highly stained in the cell body and the dendrite of pyramidal neurons in the grey matter and its level was reduced in CTE. Scale bars: black 2 µm; white 5 µm. (B) Densitometry analysis showed that TUBB3 level was significantly reduced in both the grey matter and the white matter of the cortex in CTE postmortem brain. The intensity of signals was measured at a total of 30 regions (10 regions at each slide from 3 stained slides). ^**Significantly different from normal subject at p<0.01. (C) The immunoreactivity of MAG protein, an oligodendrocyte marker, was down-regulated in both the grey matter and the white matter of the cortex in CTE postmortem brain compared to normal control. MAG was highly stained in the neuropils of the grey matter and its level was reduced in CTE. Scale bars: black 2 µm; white 5 µm. (D) Densitometry analysis showed that MAG protein level was significantly reduced in both the grey matter and the white matter of the cortex in CTE postmortem brain. The intensity of signals was measured at a total of 30 regions (10 regions at each slide from 3 stained slides). ^**Significantly different from normal subject at p<0.01.