Cyclin-kinase inhibitors (CKIs) are versatile negative regulators of cell proliferation that function in developmental decisions, checkpoint control and tumour suppression. Phenotypic examination of mice lacking individual CKIs has begun to reveal the specialized roles that each of these proteins play in vivo. This review focuses on what has been learned about the role of CKIs in development and cancer through the generation of knockout animals. The authors discuss whether differences in knockout phenotypes between CKIs reflect differential use of these inhibitors by the organism or a fundamental difference between the inhibitors, and suggest a balance hypothesis to explain the different effects observed.

中文翻译：

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平衡问题：细胞周期蛋白激酶抑制剂在发育和肿瘤发生中的作用。

细胞周期蛋白激酶抑制剂（CKI）是细胞增殖的多功能负调节剂，可在发育决定，检查点控制和肿瘤抑制中发挥作用。对缺乏单个CKI的小鼠的表型检查已开始揭示这些蛋白各自在体内发挥的特殊作用。这篇综述着重介绍了通过产生基因敲除动物了解到的CKI在发展和癌症中的作用。作者讨论了CKI之间敲除表型的差异是否反映了生物体对这些抑制剂的不同使用或抑制剂之间的根本差异，并提出了一种平衡假设来解释观察到的不同作用。