Serine/threonine-protein kinase that performs several important functions throughout M phase of the cell cycle, including the regulation of centrosome maturation and spindle assembly, the removal of cohesins from chromosome arms, the inactivation of anaphase-promoting complex/cyclosome (APC/C) inhibitors, and the regulation of mitotic exit and cytokinesis (PubMed : 11202906, PubMed : 12207013, PubMed : 12447691, PubMed : 12524548, PubMed : 12738781, PubMed : 12852856, PubMed : 12939256, PubMed : 14532005, PubMed : 14734534, PubMed : 15070733, PubMed : 15148369, PubMed : 15469984, PubMed : 16198290, PubMed : 16247472, PubMed : 16980960, PubMed : 17081991, PubMed : 17351640, PubMed : 17376779, PubMed : 17617734, PubMed : 18174154, PubMed : 18331714, PubMed : 18418051, PubMed : 18477460, PubMed : 18521620, PubMed : 18615013, PubMed : 19160488, PubMed : 19351716, PubMed : 19468300, PubMed : 19468302, PubMed : 19473992, PubMed : 19509060, PubMed : 19597481, PubMed : 23455478, PubMed : 23509069, PubMed : 28512243, PubMed : 8991084). Polo-like kinase proteins act by binding and phosphorylating proteins that are already phosphorylated on a specific motif recognized by the POLO box domains (PubMed : 11202906, PubMed : 12207013, PubMed : 12447691, PubMed : 12524548, PubMed : 12738781, PubMed : 12852856, PubMed : 12939256, PubMed : 14532005, PubMed : 14734534, PubMed : 15070733, PubMed : 15148369, PubMed : 15469984, PubMed : 16198290, PubMed : 16247472, PubMed : 16980960, PubMed : 17081991, PubMed : 17351640, PubMed : 17376779, PubMed : 17617734, PubMed : 18174154, PubMed : 18331714, PubMed : 18418051, PubMed : 18477460, PubMed : 18521620, PubMed : 18615013, PubMed : 19160488, PubMed : 19351716, PubMed : 19468300, PubMed : 19468302, PubMed : 19473992, PubMed : 19509060, PubMed : 19597481, PubMed : 23455478, PubMed : 23509069, PubMed : 28512243, PubMed : 8991084). Phosphorylates BORA, BUB1B/BUBR1, CCNB1, CDC25C, CEP55, ECT2, ERCC6L, FBXO5/EMI1, FOXM1, KIF20A/MKLP2, CENPU, NEDD1, NINL, NPM1, NUDC, PKMYT1/MYT1, KIZ, MRE11, PPP1R12A/MYPT1, POLQ, PRC1, RACGAP1/CYK4, RAD51, RHNO1, SGO1, STAG2/SA2, TEX14, TOPORS, p73/TP73, TPT1, WEE1 and HNRNPU (PubMed : 11202906, PubMed : 12207013, PubMed : 12447691, PubMed : 12524548, PubMed : 12738781, PubMed : 12852856, PubMed : 12939256, PubMed : 14532005, PubMed : 14734534, PubMed : 15070733, PubMed : 15148369, PubMed : 15469984, PubMed : 16198290, PubMed : 16247472, PubMed : 16980960, PubMed : 17081991, PubMed : 17218258, PubMed : 17351640, PubMed : 17376779, PubMed : 17617734, PubMed : 18174154, PubMed : 18331714, PubMed : 18418051, PubMed : 18477460, PubMed : 18521620, PubMed : 18615013, PubMed : 19160488, PubMed : 19351716, PubMed : 19468300, PubMed : 19468302, PubMed : 19473992, PubMed : 19509060, PubMed : 19597481, PubMed : 22325354, PubMed : 23455478, PubMed : 23509069, PubMed : 25986610, PubMed : 26811421, PubMed : 28512243, PubMed : 37440612, PubMed : 37674080, PubMed : 8991084). Plays a key role in centrosome functions and the assembly of bipolar spindles by phosphorylating KIZ, NEDD1 and NINL (PubMed : 16980960, PubMed : 19509060). NEDD1 phosphorylation promotes subsequent targeting of the gamma-tubulin ring complex (gTuRC) to the centrosome, an important step for spindle formation (PubMed : 19509060). Phosphorylation of NINL component of the centrosome leads to NINL dissociation from other centrosomal proteins (PubMed : 12852856). Involved in mitosis exit and cytokinesis by phosphorylating CEP55, ECT2, KIF20A/MKLP2, CENPU, PRC1 and RACGAP1 (PubMed : 12939256, PubMed : 16247472, PubMed : 17351640, PubMed : 19468300, PubMed : 19468302). Recruited at the central spindle by phosphorylating and docking PRC1 and KIF20A/MKLP2; creates its own docking sites on PRC1 and KIF20A/MKLP2 by mediating phosphorylation of sites subsequently recognized by the POLO box domains (PubMed : 12939256, PubMed : 17351640). Phosphorylates RACGAP1, thereby creating a docking site for the Rho GTP exchange factor ECT2 that is essential for the cleavage furrow formation (PubMed : 19468300, PubMed : 19468302). Promotes the central spindle recruitment of ECT2 (PubMed : 16247472). Plays a central role in G2/M transition of mitotic cell cycle by phosphorylating CCNB1, CDC25C, FOXM1, CENPU, PKMYT1/MYT1, PPP1R12A/MYPT1 and WEE1 (PubMed : 11202906, PubMed : 12447691, PubMed : 12524548, PubMed : 19160488). Part of a regulatory circuit that promotes the activation of CDK1 by phosphorylating the positive regulator CDC25C and inhibiting the negative regulators WEE1 and PKMYT1/MYT1 (PubMed : 11202906). Also acts by mediating phosphorylation of cyclin-B1 (CCNB1) on centrosomes in prophase (PubMed : 12447691, PubMed : 12524548). Phosphorylates FOXM1, a key mitotic transcription regulator, leading to enhance FOXM1 transcriptional activity (PubMed : 19160488). Involved in kinetochore functions and sister chromatid cohesion by phosphorylating BUB1B/BUBR1, FBXO5/EMI1 and STAG2/SA2 (PubMed : 15148369, PubMed : 15469984, PubMed : 17376779, PubMed : 18331714). PLK1 is high on non-attached kinetochores suggesting a role of PLK1 in kinetochore attachment or in spindle assembly checkpoint (SAC) regulation (PubMed : 17617734). Required for kinetochore localization of BUB1B (PubMed : 17376779). Regulates the dissociation of cohesin from chromosomes by phosphorylating cohesin subunits such as STAG2/SA2 (By similarity). Phosphorylates SGO1 : required for spindle pole localization of isoform 3 of SGO1 and plays a role in regulating its centriole cohesion function (PubMed : 18331714). Mediates phosphorylation of FBXO5/EMI1, a negative regulator of the APC/C complex during prophase, leading to FBXO5/EMI1 ubiquitination and degradation by the proteasome (PubMed : 15148369, PubMed : 15469984). Acts as a negative regulator of p53 family members : phosphorylates TOPORS, leading to inhibit the sumoylation of p53/TP53 and simultaneously enhance the ubiquitination and subsequent degradation of p53/TP53 (PubMed : 19473992). Phosphorylates the transactivation domain of the transcription factor p73/TP73, leading to inhibit p73/TP73-mediated transcriptional activation and pro-apoptotic functions. Phosphorylates BORA, and thereby promotes the degradation of BORA (PubMed : 18521620). Contributes to the regulation of AURKA function (PubMed : 18615013, PubMed : 18662541). Also required for recovery after DNA damage checkpoint and entry into mitosis (PubMed : 18615013, PubMed : 18662541). Phosphorylates MISP, leading to stabilization of cortical and astral microtubule attachments required for proper spindle positioning (PubMed : 23509069). Together with MEIKIN, acts as a regulator of kinetochore function during meiosis I : required both for mono-orientation of kinetochores on sister chromosomes and protection of centromeric cohesin from separase-mediated cleavage (By similarity). Phosphorylates CEP68 and is required for its degradation (PubMed : 25503564). Regulates nuclear envelope breakdown during prophase by phosphorylating DCTN1 resulting in its localization in the nuclear envelope (PubMed : 20679239). Phosphorylates the heat shock transcription factor HSF1, promoting HSF1 nuclear translocation upon heat shock (PubMed : 15661742). Phosphorylates HSF1 also in the early mitotic period; this phosphorylation regulates HSF1 localization to the spindle pole, the recruitment of the SCF(BTRC) ubiquitin ligase complex induicing HSF1 degradation, and hence mitotic progression (PubMed : 18794143). Regulates mitotic progression by phosphorylating RIOK2 (PubMed : 21880710). Through the phosphorylation of DZIP1 regulates the localization during mitosis of the BBSome, a ciliary protein complex involved in cilium biogenesis (PubMed : 27979967). Regulates DNA repair during mitosis by mediating phosphorylation of POLQ and RHNO1, thereby promoting POLQ recruitment to DNA damage sites (PubMed : 37440612, PubMed : 37674080). Phosphorylates ATXN10 which may play a role in the regulation of cytokinesis and may stimulate the proteasome-mediated degradation of ATXN10 (PubMed : 21857149).