The E2F pathway of growth control

癌症是由异常的细胞生长和分裂引起的，通常被描述为细胞周期疾病。细胞周期是指一个细胞生长和分裂的过程，在正常的健康细胞中，这是一个严格调节的过程。细胞周期分为四个阶段，其中一个主要的控制点存在于细胞从最初的G1期进入S期的过程中，S期是细胞开始合成和复制DNA为细胞分裂做准备的时候。在哺乳动物细胞中，E2F是一种重要的控制蛋白，因为它决定细胞是否进入S期。E2F的活性是由一些关键蛋白质，作为一个？刹车？系统，并且包括视网膜母细胞瘤肿瘤抑制蛋白（pRb），其通过与E2F形成蛋白质复合物来阻断E2F活性。最重要的是，在人类肿瘤细胞中，pRb通常是无活性的，这意味着正常严格调节的E2F活性被释放，提供了一个永久的信号，驱动细胞进入无限制的生长和分裂。这里描述的研究计划希望剖析不同类型的E2F活性的作用和调节，并评估对正常和肿瘤细胞生长的贡献。由于E2F在癌症中的异常控制，这项研究可能会发现新的治疗机会，以防止肿瘤细胞的生长。

Cancer results from abnormal cell growth and division, and is frequently described as a disease of the cell cycle. The cell cycle refers to the process through which one cell grows and divides which, in normal healthy cells, is a tightly regulated process. The cell cycle is divided into four phases, where a major point of control exists as cells progress from the initial G1 phase into S phase, which is when cells begin to synthesise and copy their DNA in preparation for cell division. In mammalian cells, E2F is a control protein of central importance because it governs whether cells do or do not enter S phase. The activity of E2F is regulated by a number of key proteins that act as a ?braking? system, and includes the retinoblastoma tumour suppressor protein (pRb) which, by forming a protein complex with E2F, blocks E2F activity. Most importantly, in human tumour cells pRb is usually inactive, which means that the normally tightly regulated E2F activity is unleashed, providing a permanent signal that drives cells into unrestrained growth and division. The programme of study described here wants to dissect the role and regulation of different types of E2F activity, and assess the contribution to normal and tumour cell growth. Because of the abnormal control of E2F in cancer, this study is likely to identify new therapeutic opportunities for preventing the growth of tumour cells.