The pro-apoptotic function of p53 has been well defined in preventing genomic instability and cell transformation. However, the intriguing fact that p53 contributes to a pro-survival advantage of tumor cells under DNA damage conditions raises a critical question in radiation therapy for the 50% human cancers with intact p53 function. Herein, we reveal an anti-apoptotic role of mitochondrial p53...

Cdc20 is an activator of the anaphase-promoting complex/cyclosome that initiates anaphase onset by ordering the destruction of cyclin B1 and securin in metaphase. To study the physiological significance of Cdc20 in higher eukaryotes, we generated hypomorphic mice that express small amounts of this essential cell cycle regulator. In this study, we show that these mice are healthy and not prone t...

The tumour suppressor protein p53 has functions in controlling the G(1)/S and G(2)/M transitions. Central regulators for progression from G(2) to mitosis are B-type cyclins complexed with cdc2 kinase. In mammals two cyclin B proteins are found, cyclin B1 and B2. We show that upon treatment of HepG2 cells with 5-fluorouracil or methotrexate, p53 levels increase while concentrations of cyclin B2 ...

The cdc2 kinase and B-type cyclins are known to be components of maturation- or M-phase-promoting factor (MPF). Phosphorylation of cyclin B has been reported previously and may regulate entry into and exit from mitosis and meiosis. To investigate the role of cyclin B phosphorylation, we replaced putative cdc2 kinase phosphorylation sites in Xenopus cyclins B1 and B2 by using oligonucleotide sit...

Background: The aim of the study was to determine mechanism Moringa oleifera-induced apoptosis in HeLa cells. cells over-express cyclin E and B1, abrogate G0-G1 G2-M cell cycle arrest, promoting tumorigenesis. Cyclin E, E2F1 telomerase expression, caspase-3 -7 activation were assessed after 24-treatment with M. oleifera leaf fractions. Material methods: Apoptosis through caspase-7 determined qu...

Cyclins are the essential regulatory subunits of cyclin-dependent protein kinases. They accumulate and disappear periodically at specific phases of the cell cycle. Here we investigated whether variations in cyclin mRNA levels in exponentially growing cells can be attributed to changes in mRNA stability. Mouse EL4 lymphoma cells and 3T3 fibroblasts were synchronized by elutriation or cell sortin...

A normal cell cycle in most eukaryotic cells consists of a tightly regulated sequence of phases including DNA synthesis (S) followed by a gap (G2), mitosis (M), and a gap (G1). In the megakaryocytic lineage, the cells undergo endomitosis, which involves DNA synthesis in the absence of mitosis, thus giving rise to polyploid cells. We aimed at defining whether the megakaryocytic cell cycle consis...