Methods for stimulating proliferation and inhibiting death of cells in the epidermis and dermis of wounded and non-wounded as well as transplanted mammalian skin and transplanted skin cell suspensions are described. The methods include the steps of administering to an area of wounded or non-wounded skin therapeutically effective amounts of .alpha..sub.1-antitrypsin, alkaline phosphatase (such as placental alkaline phosphatase), transferrin, and .alpha..sub.1-acid glycoprotein in compositions that contain at least two of these proteins, or their active derivatives, as the major active components. The compositions can be administered topically and/or by injection, or both. The invention also provides regimens for restoring or maintaining the strength and thickness of wounded, non-wounded and transplanted skin as well as developing new skin from skin cell suspensions comprising periodically administering one or more compositions topically and/or by injection.