EPO and Stroke: For example, Ren et al. [25] found that initiating osteogenic protein-1 to rats with experimental infarct 1 or 3 days, but not 7 days, post-stroke improved motor behavioral outcomes, and Kolb et al. [26] found that sequential growth factors (epidermal growth factor followed by erythropoietin) initiated 0 or 3 days post-stroke showed greater behavioral gains compared to when therapy was initiated 7 days post-stroke.