Dual specificity kinase acting on both serine/threonine and tyrosine-containing substrates. Phosphorylates serine- and arginine-rich (SR) proteins of the spliceosomal complex and may be a constituent of a network of regulatory mechanisms that enable SR proteins to control RNA splicing. Phosphorylates: SRSF1, SRSF3 and PTPN1. Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells and adenovirus E1A pre-mRNA. 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] Regulates splicing of its own pre-mRNA according to its kinase activity; increased expression of the catalytically active form influences splicing to generate the catalytically inactive splicing variant lacking the kinase domain. Leucettine L41 inhibits its kinase activity and affects the regulation of alternative splicing mediated by phosphorylation of SR proteins. Interacts with PPIG and UBL5. Autophosphorylates on all three types of residues. Lacks the kinase domain. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. Lammer subfamily.