In contrastto rodents, the increase in microglial TSPO signal in human microgliamay better reflect the cell proliferation than an increase in TSPOprotein per cell, as observed in the cortex of Alzheimer’sdisease subjects.11,14,15 It can be hypothesized that increases in TSPO are partly due toSTAT3 since an increase in STAT3 has been described in AD and stimulationof TSPO by STAT3 has been observed in nonbrain cells.16,17. Here, STAT3 is linked to Alzheimer disease.