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e14509Background: Cyclin dependent kinases (CDK) play a vital role in cell cycling and proliferation. Altered expression of these kinases in malignant cells results in deregulation of cell cycle ac...

1. 1. The glycine-arginine-rich histones isolated from bovine lymphosarcoma and Novikoff hepatoma have been found to have virtually the same amino acid compositions as that of fetal cal thymus and calf thymus published previously 8,9 . 2. 2. The glycine-arginine-rich histones isolated from fetal calf thymus, bovine lymphosarcoma and Novikoff hepatoma were cleaved with cyanogen bromide to yield two peptides. The C-terminal CN-2 peptide for each histone was isolated by the use of Sephadex G-100. The C-terminal CN-2 peptide for each of these three tissues was found to have the same amino acid composition as that from calf thymus 12 . 3. 3. The C-terminal peptides, CN-2, of bovine lymphosarcoma, fetal calf thymus and Novikoff hepatoma were hydrolyzed with trypsin. In each case five peptides were obtained by peptide mapping and ion-exchange chromatography. The amino acid compositions of these peptides were identical for each of the tissues and to that found for calf thymus previously. 4. 4. It was concluded that the C-terminal portion of the glycine-arginine-rich histones isolaetd from these four tissues are identical with each other and with that of pea seedling 11 .