Involved in cellular calcium homeostasis regulation. May participate in differentiation and apoptosis of keratinocytes. Overexpression induces apoptosis. Present at high level in epidermis and seminiferous epithelium: while basal cells in the epidermis and spermatogonia show no perceptible amount, keratinocytes of suprabasal layers and differentiating first-order spermatocytes up to spermatids exhibit high expression.