Pleiotropic regulator of mitotic progression, participating in the control of spindle dynamics and chromosome separation (PubMed:12101123, PubMed:12840024, PubMed:14660563, PubMed:19941817). Phosphorylates different histones, myelin basic protein, beta-casein, and BICD2 (PubMed:11864968). Phosphorylates histone H3 on serine and threonine residues and beta-casein on serine residues (PubMed:11864968). Important for G1/S transition and S phase progression (PubMed:12840024, PubMed:14660563, PubMed:19941817). Phosphorylates NEK6 and NEK7 and stimulates their activity by releasing the autoinhibitory functions of Tyr-108 and Tyr-97 respectively (PubMed:12840024, PubMed:14660563, PubMed:19941817, PubMed:26522158). {ECO:0000269|PubMed:11864968, ECO:0000269|PubMed:12101123, ECO:0000269|PubMed:12840024, ECO:0000269|PubMed:14660563, ECO:0000269|PubMed:19941817, ECO:0000269|PubMed:26522158}. This is the function of ENSG00000119638 (NEK9, NIMA related kinase 9).