title: Purification of a chalone-like inhibitor for Ehrlich ascites mammary carcinoma cells from bovine mammary gland.
abstract: A factor which inhibits the resumption of proliferation of stationary Ehrlich ascites mammary carcinoma (EAC) cells in vitro was isolated from the normal, lactating bovine mammary gland. After fractionation of the 50,000 g supernatant of the tissue homogenate by ammonium sulfate precipitation and gel filtration, it was further purified 2600-fold by ultrafiltration and lectin affinity chromatography. Polyacrylamide electrophoresis revealed one band containing all the activity. SDS gel electrophoresis showed a main band corresponding to a protein with a molecular weight of about 15,000 dalton. At this state of purity the factor concentration for half-maximal inhibition of proliferation was 12 ng/ml or 8 X 10(-10) M. The effects of factor concentrations of 4 X 10(-9) or 4 X 10(-8) M are abolished by 5 X 10(-9) M insulin almost completely or to 70%.
mesh_terms: D000818:Animals; D002286:Carcinoma, Ehrlich Tumor / Q000473:pathology*; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002460:Cell Line; D002846:Chromatography, Affinity; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D004589:Electrophoresis, Disc; D004591:Electrophoresis, Polyacrylamide Gel; D006131:Growth Inhibitors / Q000302:isolation & purification* / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D008321:Mammary Glands, Animal / Q000032:analysis*; D008325:Mammary Neoplasms, Experimental / Q000473:pathology*; D014462:Ultrafiltration
chemical_list: D006131:Growth Inhibitors; D007328:Insulin