Neurotrophic and neuroprotective effect of EPO on SMI 32-positive motoneurons in mixed neuron/glia cultures. (A) Motoneurons in control cultures, well defined morphologically. (B) Control cultures 5 days after administration of EPO (2.5 pmol/mL) alone: large cell bodies with long axons and an increase of cell number can be seen. (C) Cultures treated for 48 h with 5 µM kainate. (D) Effect of EPO (added 3 days before and during kainate exposure) on cultures treated with kainate. Motoneurons were stained using an anti-nonphosphorylated neurofilament monoclonal antibody (SMI 32) as described in Materials and Methods. Scale bar = 100 µm.