KLK1 and androgen insensitivity syndrome: In animal models of AIS, the expression of the BK2 receptor in the endothelial cells was found to increase 36-fold in the ipsilateral middle cerebral artery, compared with a contralateral increase of 10-fold.16 Thus, the binding of KLK1 produces bradykinin, and in AIS, it capitalizes on the upregulated BK2 receptors for improving brain perfusion under ischemic conditions by enhancing focal vasodilation in the ischemic penumbra and augmenting local cerebral blood flow without significantly affecting systemic blood pressure.