• cyclin-dependent kinase inhibitor;
  • p18INK4C;
  • ATL;
  • tumour suppressor gene;
  • cell cycle

p18INK4C, a cyclin-dependent kinase inhibitor, is a homologue of p15INK4B and p16INK4A which are frequently altered in a variety of malignancies. We searched for structural alterations of the p18INK4C gene in 44 adult T-cell leukaemias (ATLs), 101 non-Hodgkin's lymphomas (NHLs), two polyclonal B-cell proliferations, seven ATL cell lines and seven leukaemia/lymphoma cell lines, by Southern blot and polymerase chain reaction–single-strand conformation polymorphism (PCR-SSCP) analyses. No genomic alterations of the p18INK4C gene were found in any of the samples. By RT-PCR, p18INK4C was not expressed in three of five ATL cell lines, whereas it was expressed in all the non-ATL leukaemia/lymphoma cell lines. Tax did not inhibit the expression of p18INK4C in tax-expressing Jurkat cells.