CHEK1编码蛋白（Checkpoint Kinase 1）是丝氨酸/苏氨酸激酶（一种细胞内激酶），在DNA损伤检查点通路中起着不可或缺的作用，并防止受损细胞继续通过细胞周期。CHEK1被ATR和ATM激酶通过磷酸化而激活，用来响应DNA损伤。一旦被激活，CHEK1充当效应激酶，介导下游信号传导，其导致多种细胞应答包括细胞周期检查点激活，细胞周期停滞，DNA修复和/或细胞凋亡和复制叉稳定性。CHEK1在多种肿瘤中常过度表达，包括乳腺癌、非小细胞肺癌和鼻咽癌，但是CHEK1在肿瘤中发生的频率并不高。

CHEK1 (Checkpoint Kinase 1) is a serine/threonine kinase that plays an integral role in the DNA damage checkpoint pathway and prevents damaged cells from continuing through the cell cycle. In response to DNA damage, CHEK1 is activated by the kinases ATR and ATM via phosphorylation. Once activated, CHEK1 acts as an effector kinase, mediating downstream signaling that leads to a diverse range of cellular responses, including cell cycle checkpoint activation, cell cycle arrest, DNA repair and/or apoptosis and replication fork stability. In particular, activated CHEK1 maintains the cyclin B1-CDK1 complex in an inactive cytoplasmic state, which prevents the G2/M transition and prevents mitotic segregation of damaged chromatids. Though CHEK1 mutations are extremely rare CHEK1 is frequently over-expressed in a variety of tumors, including breast, non-small cell lung cancer, and nasopharyngeal cancers.

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