Abstract. Cell cycle-dependent phosphorylation and nuclear import of the tumorigenic transcription factor viral Jun (v-Jun) were investigated in chicken embryo fibroblasts. Nuclear accumulation of v-Jun but not of cellular Jun (c-Jun) is cell cycle dependent, decreasing in G1 and increasing in G2. The cell cycle-dependent regulation of v-Jun was mapped to a single serine residue at position 248 (Ser248), adjacent to the nuclear localization signal (NLS). Ser 248 of v-Jun represents an amino acid substitution, replacing cysteine of c-Jun. It was shown by peptidase digestion and immunoprecipitation with antibody to the NLS that v-Jun is phosphorylated at Ser 248 in the cytoplasm but not in the nucleus. This phosphorylation is high in G1 and low in G2. Nuclear accumulation of v-Jun is correlated with underphosphorylation at Ser 248. The regulation of nuclear import by phosphorylation was also examined using NLS peptides with Ser 248 of v-Jun. Phosphorylation of the serine inhibited nuclear import mediated by the NLS peptide in vivo and in vitro. The protein kinase inhibitors staurosporine and H7 stimulated but the phosphatase inhibitor okadaic acid inhibited nuclear import mediated by the NLS peptide. The cytosolic activity of protein kinases phosphorylating Ser 248 increased in GO and decreased during cell cycle progression, reaching a minimum in G2, whereas phosphatase activity dephosphorylating Ser 248 was not changed. These results show that nuclear import of v-Jun is negatively regulated by phosphorylation at Ser 24s in the cytoplasm in a cell cycle-dependent manner.UKARYOTIC cells contain various intracellular membranous organelles that compartmentalize special functions. Specific sorting mechanisms accumulate proteins at their sites of function. In DNA transcription and replication, the movement of proteins from their cytoplasmic site of synthesis to the nuclear interior occurs by translocation across the nuclear pore, a component of the nuclear membrane (for recent review see Dingwall and Laskey, 1992;Forbes, 1992). The nuclear pore complex is a large proteinaceous structure forming a channel with an M r of 125,000 kD, consisting of >100 different proteins, including nucleoporins (Davis and Blobel, 1986;Reichelt et al., 1990;Hinshaw et al., 1992). Small molecules freely pass through the pore by diffusion, but larger proteins are specifically selected to enter the nucleus. The nuclear import of proteins is mediated by short amino acid sequences present in most nuclear proteins and known as nuclear localization signals (NLSs) 1 (Kalderon et al., 1984a, b;Garcia-Bustos et al., 1991).

Purpose. Chemotherapy has been tested extensively in conjunction with standard therapy in the treatment of head and neck cancer, primarily in the form of neoadjuvant chemotherapy, but few trials have shown a survival benefit. Although a few studies have suggested that adjuvant chemotherapy given after standard treatment may improve survival, to date these trials have been troubled by various problems in design and dosing. The purpose of our trial was to determine the feasibility of giving moderately intensive chemotherapy exclusively after standard therapy, and to determine whether survival appeared to be improved as measured against historical data. Methods. We used adjuvant chemotherapy in two groups of patients with squamous cell carcinoma of the head and neck: group A consisted of 46 patients with newly diagnosed stage III and IV disease, and group B consisted of 46 patients with relapsed disease having been treated with salvage surgery. In all patients, the intended adjuvant chemotherapy consisted of two cycles of combination cisplatin, bleomycin, and infusional 5‐fluorouracil (5‐FU) given three weeks apart, followed by four cycles of bolus methotrexate, 5‐FU, and bleomycin given every two weeks. Results. In group A, the two‐year survival was 72%. In group B, the two‐year survival was 58%. Conclusion. Compared to the vast majority of similarly staged patients with head and neck cancer reported in the literature, the survival of our group seemed considerably better, suggesting that a definitive randomized study testing this schedule of adjuvant chemotherapy is warranted.

To eliminate health disparities between Latinos and whites, future health policy and public health efforts should target diabetes, homicide, HIV, and liver disease among Latinos and lung cancer among whites.

A suppression subtractive hybridization technique was used to identify reactive oxygen species (ROS)-regulated genes in rat vascular smooth muscle cells. Three genes out of 89 clones, identified as fibronectin, p105 coactivator and ECA39, showed increased expression after treatment with H 2 O 2 . The mRNA expressions of these three genes were induced in a time-and dosedependent manner, independent of protein kinase C activation. Immunohistochemical staining showed that the p105 coactivator expression was markedly induced in the neointima of ballooninjured rat carotid arteries. These results suggest that ROS may play an important role in the development of atherosclerosis by regulating the gene expressions we identified in this study.z 1999 Federation of European Biochemical Societies.