The ARF tumor suppressor is widely regarded as an upstream activator of p53-dependent growth arrest and apoptosis. However, recent findings indicate that ARF can also regulate the cell cycle in the absence of p53. In search of p53-independent ARF targets, we isolated nucleophosmin (NPM/B23), a protein we show is required for proliferation, as a novel ARF binding protein. In response to hyperpro...

Acute uremia (ARF) causes metabolic defects in glucose and protein metabolism that contribute to muscle wasting. To examine whether there are also defects in the metabolism of essential amino acids in ARF, we measured the activity of the rate-limiting enzyme for branched-chain amino acid catabolism, branched-chain ketoacid dehydrogenase (BCKAD), in rat muscles. Because chronic acidosis activate...

The CDKN2A/ARF locus encompasses overlapping tumor suppressor genes p16(INK4A) and p14(ARF), which are frequently co-deleted in human malignant mesothelioma (MM). The importance of p16(INK4A) loss in human cancer is well established, but the relative significance of p14(ARF) loss has been debated. The tumor predisposition of mice singly deficient for either Ink4a or Arf, due to targeting of exo...

Translation of mRNA in alternate reading frames (ARF) is a naturally occurring process heretofore underappreciated as a generator of protein diversity. The MUC1 gene encodes MUC1-TM, a signal-transducing trans-membrane protein highly expressed in human malignancies. Here we show that an AUG codon downstream to the MUC1-TM initiation codon initiates an alternate reading frame thereby generating ...

Inactivation of the Arf-Mdm2-p53 tumor suppressor pathway is a necessary event for tumorigenesis. Arf controls Mdm2, which in turn regulates p53, but Arf and Mdm2 also have p53-independent functions that affect tumor development. Moreover, inhibition of oncogene-induced tumorigenesis relies on Arf and p53, but the requirements of Arf and p53 in tumor development initiated in the absence of over...

ARF is an alternative reading frame product of the INK4a/ARF locus, inactivated in numerous human cancers. ARF is a key regulator of cellular senescence, an irreversible cell growth arrest that suppresses tumor cell growth. It functions by sequestering MDM2 (a p53 E3 ligase) in the nucleolus, thus activating p53. Besides MDM2, ARF has numerous other interacting partners that induce either cellu...

ARF encodes a potent tumor suppressor that antagonizes MDM2, a negative regulator of p53. ARF also suppresses the proliferation of cells lacking p53, and loss of ARF in p53-null mice, compared with ARF or p53 singly null mice, results in a broadened tumor spectrum and decreased tumor latency. To investigate the mechanism of p53-independent tumor suppression by ARF, potential interacting protein...

The INK4a-ARF locus encodes two proteins, p16(INK4a) and p19(ARF), that restrain cell growth by affecting the functions of the retinoblastoma protein and p53, respectively. Disruption of this locus by deletions or point mutations is a common event in human cancer, perhaps second only to the loss of p53. Using insect cells infected with baculovirus vectors and NIH 3T3 fibroblasts infected with A...

Senescence, a state of stable growth arrest, plays an important role in ageing and age-related diseases vivo. Although the INK4/ARF locus is known to be essential for senescence programmes, key regulators driving p16 ARF transcription remain largely underexplored. Using siRNA screening modulators p16/pRB ARF/p53/p21 pathways deeply senescent human mammary epithelial cells (DS HMECs) fibroblasts...

The p14(ARF) protein directly inhibits the MDM-2 oncoprotein, which mediates degradation of the p53 protein. It has been shown that p14(ARF) expression is frequently down-regulated by p14(ARF) gene hypermethylation in colorectal cancer. To determine whether p14(ARF) inactivation was involved in ulcerative colitis (UC)-associated carcinogenesis, the frequency and timing of p14(ARF) methylation w...