Abstract:
Members of the InK4 (Inhibitors of CDK4) family inhibit the activities of specific cyclin D-dependent kinases (CDK4 and/or CDK6), thereby arresting cell cycle progression in G1 phase and preventing chromosomal DNA replication. Disclosed herein are novel mammalian InK4 family members, having apparent molecular masses of 18,000 and 19,000 daltons, designated "InK4c-p18" and "InK4d-p19," respectively, or simply "p18" and "p19. " In particular, the invention provides p19 genes and proteins isolated from murine or human cells and p18 genes and proteins from murine cells. When constitutively expressed in cells, p19 inhibits cyclin D-dependent kinase activity in vivo and induces G1 phase arrest. Materials and methods disclosed herein include (1) nucleic acids that encode p18 or p19; (2) methods for detecting nucleic acids encoding p18 or p19 proteins; (3) methods for producing p18 or p19 proteins using nucleic acids that encode p18 or p19, respectively; (4) purified pl8 or p19 proteins and peptide fragments, oligopeptides, or fusion proteins derived therefrom; (5) methods of inhibiting cells from replicating their chromosomal DNA using purified p18 or p19 proteins or derivatives thereof; (6) antibodies that specifically bind p18 or p19; (7) methods for detecting p18 and p19 proteins; (8) methods of stimulating cell growth by blocking p18 or p19 expression via antisense oligonucleotides; (9) methods of gene therapy using nucleic acids that encode p18 or p19; and (10) methods of making transgenic non-human animals that have alterations in the gene encoding p18 or p19, or in both genes.