Serine/threonine kinase involved in spliceosomal assembly as well as mitosis and signaling regulation (PubMed:10799319, PubMed:12077342, PubMed:17513757, PubMed:17998396). Connects chromatin mediated regulation of transcription and pre-mRNA splicing (PubMed:12077342). During spliceosomal assembly, interacts with and phosphorylates PRPF6 and PRPF31, components of the U4/U6-U5 tri-small nuclear ribonucleoprotein (snRNP), to facilitate the formation of the spliceosome B complex. Plays a role in regulating transcription and the spindle assembly checkpoint (SAC) (PubMed:20118938). Associates with U5 snRNP and NCOR1 deacetylase complexes which may allow a coordination of pre-mRNA splicing with chromatin remodeling events involved in transcriptional regulation (PubMed:12077342). Associates and probably phosphorylates SMARCA4 and NCOR1 (PubMed:12077342). Phosphorylates SRSF1 (PubMed:11418604). Associates with kinetochores during mitosis and is necessary for recruitment and maintenance of the checkpoint proteins such as MAD1L1 and MAD12L1 at the kinetochores (PubMed:17998396). Phosphorylates and regulates the activity of the transcription factors such as ELK1 and KLF13 (PubMed:10799319, PubMed:17513757). Phosphorylates nuclear YAP1 and WWTR1/TAZ which induces nuclear exclusion and regulates Hippo signaling pathway, involved in tissue growth control (PubMed:29695716).