Methods of treating an immune disease, cell proliferation, restenosis and vascular smooth muscle cells using the pharmaceutical compounds of the formula ##STR1## in which R.sup.2 is phenyl, naphthyl or heteroaryl selected from thienyl, pyridyl, benzothienyl, quinolinyl, benzofuranyl or benzimidazolyl, said phenyl, naphthyl and heteroaryl groups being optionally substituted, or R.sup.2 is furanyl optionally substituted with C.sub.1-4 alkyl; and salts thereof.