Response elements named for this compound can be found in the promoter region of the Dicer gene, where it can be bound by RXR. This compound is hydroxylated in the 25-position by an enzyme that is regulated by the secretion of PTH. Corticosteroids like dexamethasone decrease levels of this compound in the body by regulating this compound’s namesake receptor. A derivative of this compound called calcipotriol is used to treat psoriasis. Bowed legs and bone fractures can result from a deficiency of this compound called rickets. This compound can be synthesized in the body from 7-dehydrocholesterol in the presence of UVB radiation. (10[1])For 10 points, what fat-soluble vitamin is synthesized through exposure to sunlight? ■END■