HSD-11β Type 2 is expressed by aldosterone-selective tissues and protects the mineralocorticoid receptor from the activation by cortisol by converting it to cortisone using the enzyme 11-Oxoreductase. HSD-11β Type 2 protects tissues from continuous activation by decreasing local cortisol levels and preventing 11-Oxoreductase from activating. In tissues that do not express the mineralocorticoid receptor, such as the placenta and testis, it protects cells from the growth-inhibiting and/or pro-apoptotic effects of cortisol, particularly during embryonic development. Mutations in this gene cause the syndrome of apparent mineralocorticoid excess and hypertension.