Enrichment analysis (Kyoto Encyclopedia of Genes and Genomes [KEGG]) revealed several activated neurodegenerative pathways involved in Parkinson’s disease or amyotrophic lateral sclerosis and proteasome activation (Figure 4C), as several proteasome-related genes, such as proteasome 20S subunits α and β (PSMA2/3/5, PSMB2/4/6/7), were upregulated in PMS astrocyte–cocultured neurons. Here, PSMB2 is linked to amyotrophic lateral sclerosis.