this invention provides pharmaceutical uses for 2 - methylene - 19 - nor - 20 - 1α , 25 - dihydroxyvitamin d 3 . this compound is characterized by high bone calcium mobilization activity demonstrating preferential activity on bone . this results in a novel therapeutic agent for the treatment of diseases where bone formation is desired , particularly osteoporosis . this compound also exhibits pronounced activity in arresting the proliferation of undifferentiated cells and inducing their differentiation to the monocyte thus evidencing use as an anti - cancer agent and for the treatment of skin diseases such as psoriasis . this compound also increases both breaking strength and crushing strength of bones evidencing use in conjunction with bone replacement surgery such as hip and knee replacements .