Tian, Jean Q., and Andrea Quaroni. Involvement of p21(WAF1/Cip1) and p27(Kip1) in intestinal epithelial cell differentiation. Am. J. Physiol. 276 (Cell Physiol. 45): C1245– C1258, 1999.—Using the conditionally immortalized human cell line tsFHI, we have investigated the role of cyclindependent kinase inhibitors (CKIs) in intestinal epithelial cell differentiation. Expression of cyclins, cyclin-...

We have cloned cDNAs for Caenorhabditis elegans cyclins A1, B and B3. While cyclins A1 and B are most closely related to either A- or B-type cyclins of other species, cyclin B3 is less related to these cyclins. However, this cyclin is most similar to the recently identified chicken cyclin B3. Our identification of a Caenorhabditis homolog demonstrates that cyclin B3 has been conserved in evolut...

Kaposi’s sarcoma-associated herpesvirus (KSHV) has a key etiological role in development of Kaposi’s sarcoma (KS). v-Cyclin is a KSHVencoded homologue to D-type cyclins that associates with cellular cyclindependent kinase 6 (CDK6). v-Cyclin promotes S-phase entry of quiescent cells and has been suggested to execute functions of both Dand E-type cyclins. In this study, expression of v-cyclin in ...

We have measured the levels of cyclin mRNAs and polypeptides during oogenesis, progesterone-induced oocyte maturation, and immediately after egg activation in the frog, Xenopus laevis. The mRNA for each cyclin is present at a constant level of approximately 5 x 10(7) molecules per oocyte from the earliest stages of oogenesis until after fertilization. The levels of polypeptides show more comple...

Although all three D cyclins bind and activate cdks 2, 4 and 6, Fbxo7 has been characterised as a selective enhancer of cdk6 activity. It increases activation by directly facilitating cdk6 interaction with viral and cellular D cyclins. Fbxo7 overexpression has transforming activity in murine fibroblasts, and it is also highly expressed in human cancers, suggesting it is a potential oncogene. Fb...

Protein phosphorylation by the complexes of cyclin and cyclin-dependent kinase plays a key role in cell cycle progression in all eukaryotes. The amplification by polymerase chain reaction of a cyclin box from developing root nodules and root apices of soybean showed the expression of a number of different molecular species of mitotic cyclins in plant meristems, and they were classified into fiv...

Mitosis is thought to be triggered by the activation of Cdk-cyclin complexes. Here we have used RNA interference (RNAi) to assess the roles of three mitotic cyclins, cyclins A2, B1, and B2, in the regulation of centrosome separation and nuclear-envelope breakdown (NEB) in HeLa cells. We found that the timing of NEB was affected very little by knocking down cyclins B1 and B2 alone or in combinat...