Dual-specificity kinase which possesses both serine/threonine and tyrosine kinase activities (PubMed:18938227). Plays an important role in double-strand breaks (DSBs) repair following DNA damage. Mechanistically, phosphorylates RNF169 and increases its ability to block accumulation of TP53BP1 at the DSB sites thereby promoting homologous recombination repair (HRR) (By similarity). May play a role in a signaling pathway regulating nuclear functions of cell proliferation. Modulates alternative splicing by phosphorylating the splice factor SRSF6 (By similarity). Exhibits a substrate preference for proline at position P+1 and arginine at position P-3. Has pro-survival function and negatively regulates the apoptotic process. Promotes cell survival upon genotoxic stress through phosphorylation of SIRT1. This in turn inhibits TP53 activity and apoptosis (PubMed:20167603). Phosphorylates SEPTIN4, SEPTIN5 and SF3B1 at 'Thr-434' (PubMed:18938227). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] ATP + L-tyrosyl-[protein] = ADP + H(+) + O-phospho-L-tyrosyl-[protein] Inhibited by RANBP9. Interacts with RANBP9 (By similarity). Interacts with RAD54L2/ARIP4 (PubMed:15199138). Interacts with WDR68 (By similarity). Interacts with CRY2 (PubMed:20123978). Interacts with SIRT1 (PubMed:20167603). Interacts with SEPTIN4 and SEPTIN5 (PubMed:18938227). Detected in brain (at protein level) (PubMed:22998443). Expressed in a variety of embryonic and adult tissues (PubMed:8975710). Expressed abundantly in neurons of the brain, spinal cord, and retina in developing embryos (PubMed:8975710). Expressed in the entorhinal, temporal and visual cortices and the hippocampus of the brain where is colocalizes with SEPTIN4 (PubMed:18938227). Expressed and extensively colocalizes with SEPTIN4 in apical dendrites of pyramidal cells (PubMed:18938227). Also expressed in Purkinje cells in the cerebellum in postnatal day 1 and adult mice (PubMed:18938227). The polyhistidine repeats act as targeting signals to nuclear speckles. Autophosphorylated on numerous tyrosine residues. Can also autophosphorylate on serine and threonine residues (in vitro) (By similarity). Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. MNB/DYRK subfamily.