A: Primary rat hippocampal neurons were transduced with constructs expressing GFP-tagged TDP-25 (amino acids 220-414 of TDP-43) on day 5 in vitro and cultured for 8 additional days (DIV5+8). Wild-type or variant containing 8 ALS-causing mutations. Immunofluorescence shows disease-related phosphorylation at serine 403/404. Counterstain to label the neuronal cytoskeleton (MAP2) and nuclei (DAPI). 