Ointment containing 1,25-dihydroxy-22-oxavitamin D3 (maxacalcitol), a noncalcemic analog of the active form of vitamin D3, is applied for the treatment of hyperkeratotic cutaneous conditions such as psoriasis and ichtyosis because it suppresses the proliferation and promotes the differentiation of keratinocytes through interaction with the vitamin D receptor. The gene discussed is VDR; the disease is psoriasis.