Effect of partial HIF-1α knockdown in cerebellar granule neurons: Cerebellar granule neurons were transfected with siRNA directed against HIF-1α and a non-targeting siRNA pool, which was used as control (control siRNA). After 3 days in culture cells were exposed to hypoxia (1% oxygen) for 6-8 hours. Prior to hypoxic insult cells were treated without purine nucleosides (Co) or with 500μM adenosine (Ado) and inosine (Ino) respectively. (A) Panels a-c and g-i indicate cell death in hypoxia in cells transfected with control and HIF-1α siRNA. Cells were stained with Hoechst (blue) and propidium iodide (PI, pink). Panels d-f and j-l show representative phase contrast pictures of the same cells. (Left panel) The percent of HIF-1α downregulation is shown for cells transfected with control siRNA (grey) and HIF-1α siRNA (black). (B) The percent of cells protected from hypoxia by purine nucleosides is shown for cells transfected with HIF-1α and control siRNA. Values represent the mean ± S.E.M., n=6. Differences were analyzed using unpaired one-tailed t-test: (B) *p<0.05. Scale bar: (A) 20μm.