Dual-specificity kinase which possesses both serine/threonine and tyrosine kinase activities (  ). Exhibits a substrate preference for proline at position P+1 and arginine at position P-3 . 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) . Also acts as a positive regulator of transcription by acting as a CTD kinase that mediates phosphorylation of the CTD (C-terminal domain) of the large subunit of RNA polymerase II (RNAP II) POLR2A (, ). 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). Has pro-survival function and negatively regulates the apoptotic process (By similarity). Promotes cell survival upon genotoxic stress through phosphorylation of SIRT1 (By similarity). This in turn inhibits p53/TP53 activity and apoptosis (By similarity). Phosphorylates SEPTIN4, SEPTIN5 and SF3B1 at 'Thr-434' (By similarity).
Subcellular locations: Nucleus, Nucleus speckle
Ubiquitous. Highest levels in skeletal muscle, testis, fetal lung and fetal kidney.