The cyclin-dependent kinase (CDK) inhibitors, p18 and p16, both have the credentials of tumor suppressors in human cancers andmousemodels. For p16, the underlying rationale is its role in senescence, but the selective force for inactivation of p18 in incipient cancer cells is less clear. Here, we show that in human fibroblasts undergoing replicative or oncogene-induced senescence, there is amar...

Pluripotent stem cells (PSCs), including embryonic and induced pluripotent stem cells (iPSCs), show atypical cell cycle regulation characterized by a high proliferation rate and a shorter G1 phase compared with somatic cells. The mechanisms by which somatic cells remodel their cell cycle to achieve the high proliferation rate of PSCs during reprogramming are unclear. Here we identify that the I...

Monoclonal antibodies which react specifically with the nuclei of interphase cells recognized three nuclear antigens with molecular weights of 110,000 (p110), 85,000 (p85), and 18,000 (p18). p110 and p85 were found in eight tumor cell lines but were not found in resting lymphocytes. p18 was found in resting lymphocytes as well as the tumor cell lines. Protein p85 appeared in phytohemagglutinin-...

Using recombinant 15- to 30-kDa fragments and fusion with glutathione S-transferase (GST), we investigated the seroreactivity of three large structural proteins of Epstein-Barr virus (EBV), p150 (BcLF1, capsid), p143 (BNRF1, tegument), and gp125 (BALF4, membrane) in Western blots. None of 13 fragments tested, however, was qualified for diagnostic application. In contrast, the two small viral ca...

The sequences coding for the p18 protein of CBL-1, a British human immunodeficiency virus (HIV) type 1 isolate, were expressed in Escherichia coli as beta-galactosidase fusion proteins. The recombinant proteins were used to screen a panel of five monoclonal antibodies (MAbs) raised against p18 expressed in CBL-1-infected cells. The regions containing the epitopes for four of the MAbs were locat...

OBJECTIVE Study 1: Introduce and validate a method for measuring EBV p18-VCA antibodies in whole blood spots to provide a minimally invasive marker of cell-mediated immune function. Study 2: Apply this method to a large community-based study of psychopathology in children and adolescents. METHODS The EBV antibody method was evaluated through analysis of precision, reliability, stability, and ...

Hematopoietic stem cells (HSCs) have emerged as promising therapeutic cell sources for high-risk hematological malignancies and immune disorders. However, their clinical use is limited by the inability to expand these cells ex vivo. Therefore, there is an urgent need to identify specific targets and effective probes that can expand HSCs. Here we report a novel class of INK4C (p18(INK4C) or p18)...

Bovine leukemia virus (BLV) and the human T-cell leukemia virus types I and II comprise a unique retrovirus subfamily which has evolved complex strategies for the regulation of gene expression. A transcriptional control circuit has been characterized in both human and bovine systems in which cis-acting promoter control elements are responsive to trans-acting factors encoded in the pX region of ...

Monoclonal antibodies were raised against the gag proteins of a British isolate of the human immunodeficiency virus (HIV), CBL-1. Seven of the monoclonal antibodies recognized HIV gag-coded proteins of 55,000 mol. wt. (p55) and 24,000 mol. wt. (p24), three recognized p55/p18 and three p18 alone. Cross-competition assays suggested that at least two independent epitopes exist on the p24 cleaved f...

The INK4 (inhibitor of cyclin-dependent kinase 4) family consists of four tumor-suppressor proteins: p15(INK4B), p16(INK4A), p18(INK4C), and p19(INK4D). While their sequences and structures are highly homologous, they show appreciable differences in conformational flexibility, stability, and aggregation tendency. Here, p16 and p18 were first compared directly by NMR for line broadening and disa...