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Updated: Jun 28, 2026

Identification of Cyclin-dependent Kinase 1 Specific Phosphorylation Sites by an In Vitro Kinase Assay
Published on: May 3, 2018
Nucleophosmin is required for chromosome congression, proper mitotic spindle formation, and kinetochore-microtubule
Mohammed Abdullahel Amin1, Sachihiro Matsunaga, Susumu Uchiyama
1Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Osaka, Japan.
Abstract:
Nucleophosmin (NPM) is an abundantly expressed multifunctional nucleolar phosphoprotein. Here we show that depletion of NPM by RNA interference causes defects in cell division, followed by an arrest of DNA synthesis due to activation of a p53-dependent checkpoint response in HeLa cells. Depletion of NPM leads to mitotic arrest due to spindle checkpoint activation. The mitotic cells arrested by NPM depletion have defects in chromosome congression, proper mitotic spindle and centrosome formation, as well as defects in kinetochore-microtubule attachments. Loss of NPM thus causes severe mitotic defects and delayed mitotic progression. These findings indicate that NPM is essential for mitotic progression and cell proliferation.
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