C3 and neurodegenerative disease: Nevertheless, considering transcriptional changes were determined using astrocytic cultures grown in media containing serum known to impact changes in gene expression and protein level, further transcriptomics studies using astrocytes grown in serum-free media which more closely mimic their acutely purified state49 and brain samples will be necessary to dissect these differences in detail and, most importantly, to establish how many subtypes of C3+ astrocytes are present in the human brain under proinflammatory conditions, such as in neurodegenerative diseases.