Studies in rodents have shown an increased expression of the enzyme in reactive astrocytes in the regions of the neural tissue affected by secondary neurodegeneration after middle cerebral artery occlusion.15,102 This, together with the demonstration that estradiol generated by astrocytes after ischemic brain injury is neuroprotective,103 suggests a direct participation of aromatase activity in the outcome of stroke. The gene discussed is CYP19A1; the disease is stroke disorder.