The cyclin D-dependent kinases CDK4 and CDK6 trigger phosphorylation of the retinoblastoma protein (RB) late in G1 phase, helping to cancel its growth-suppressive function and thereby facilitating S-phase entry. Although specific inhibition of cyclin D-dependent kinase activity in vivo can prevent cells from entering S phase, it does not affect S-phase entry in cells lacking functional RB, impl...

Differential display identified that gene fragment HA220 homologous to the transcriptional activator factor II 250 (TAFII250) gene, or CCG1, was increased in hypertrophied rodent heart. To determine whether TAFII250 gene expression is modified after cardiac damage, we measured TAFII250 expression in vivo in mouse hearts after injection of the cardiotoxic agent doxorubicin (DXR) and in vitro in ...

Cell cycle transitions are governed by the timely expression of cyclins, the activating subunits of Cyclin-dependent kinases (Cdks), which are responsible for the inactivation of the pocket proteins. Overexpression of cyclins promotes cell proliferation and cancer. Therefore, it is important to understand the mechanisms by which cyclins regulate the expression of cell cycle promoting genes incl...

In this issue of Cell, Geng et al. report that mice can undergo embryonic development without cyclins E1 and E2. Fibroblasts derived from the double knockout embryos proliferate normally in culture. However, E type cyclins seem essential for endoreplication and exit from quiescence.

Phosphorylation is a key event in cell cycle control, and dysregulation of this process is observed in many tumors, including those associated with specific inherited neoplasia syndromes. We have shown previously that patients with the autosomal dominant tumor predisposition Carney complex carry inactivating mutations in the PRKAR1A gene, which encodes the type 1A regulatory subunit of protein ...

Despite recent improvements in surgical and radiation therapy, failures still occur in patients with laryngeal squamous cell carcinomas, which may have a very different clinical outcome even when their clinical and histopathological characteristics are similar. The apparent inadequacy of "traditional" prognostic factors in predicting the clinical evolution of laryngeal squamous cell carcinomas ...

The cell division cycle is a fundamental and highly complex process that lies at the core of every proliferating cell. Progression of the eukaryotic cell through four phases — G1, S, G2 and M — ensures that genetic information is first faithfully replicated (during S phase) and then equally distributed to two daughter cells (during M phase). The function of G1 and G2 is to prepare the cell for ...

BACKGROUND . PHO85 encodes the catalytic subunit of a cyclin-dependent kinase (Cdk) in budding yeast and functions in phosphate and glycogen metabolism. Pho85 associated with the G1 cyclins Pcl1 and Pcl2 is also required for cell cycle progression in the absence of the Cdc28 cyclins Cln1 and Cln2. Loss of Pcl1, Pcl2 and related Pho85 cyclins results in budding defects, suggesting that Pcl-Pho85...

The cell cycle is a highly conserved mechanism that controls the cells decision to proliferate and regulate the process once it starts. Typically, the cell cycle is divided into four phases, namely G1 (first gap), S (DNA synthesis), G2 (second gap), and M (mitosis). The cell cycle process is regulated by the sequential expression, activation, and inhibition of Cyclin-dependent kinases (CDKs) as...