To assess protein-level changes, we performed co-immunofluorescence imaging of ERBB4 and SOX9 (pan-astrocyte marker) as well as ERBB4 and VIM (reactive astrocyte marker) on normal and AD brains (summary characteristics in Additional file 1: Table S2, individual characteristics in Additional file 1: Table S3). Here, ERBB4 is linked to Alzheimer disease.