Pleiotropic regulator of mitotic progression, participating in the control of spindle dynamics and chromosome separation. Phosphorylates different histones, myelin basic protein, beta-casein, and BICD2. Phosphorylates histone H3 on serine and threonine residues and beta-casein on serine residues. Important for G1/S transition and S phase progression. Phosphorylates NEK6 and NEK7 and stimulates their activity by releasing the autoinhibitory functions of Tyr-108 and Tyr-97 respectively. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated during mitosis by intramolecular autophosphorylation. Activity and autophosphorylation is activated by manganese >> magnesium ions. Sensitive to increasing concentration of detergents. It is not cell-cycle regulated but activity is higher in G0-arrested cells. Homodimer. Binds to Ran GTPase. Has a greater affinity for Ran-GDP over Ran-GTP. Interacts with NEK6, NEK7 and BICD2. Interacts with SSRP1 and SUPT16H, the 2 subunits of the FACT complex. Interacts with DYNLL1; phosphorylation at Ser-944 strongly reduces DYNLL1 binding. Most abundant in heart, liver, kidney and testis. Also expressed in smooth muscle cells and fibroblasts. Expression varied mildly across the cell cycle, with highest expression observed in G1 and stationary-phase cells. Dimerizes through its coiled-coil domain. Autophosphorylated on serine and threonine residues (PubMed:27153399). When complexed with FACT, exhibits markedly elevated phosphorylation on Thr-210. During mitosis, not phosphorylated on Thr-210. Phosphorylated by CDK1 in vitro. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. The disease is caused by variants affecting the gene represented in this entry. Belongs to the protein kinase superfamily. NEK Ser/Thr protein kinase family. NIMA subfamily. Extended N-terminus.