Serine/threonine-protein kinase involved in transcription regulation, apoptosis and steroidogenic gene expression. Phosphorylates JUN and RUNX2. Seems to negatively regulate apoptosis by promoting FADD phosphorylation. Enhances androgen receptor-mediated transcription. May act as a transcriptional corepressor for NK homeodomain transcription factors. The phosphorylation of NR5A1 activates SF1 leading to increased steroidogenic gene expression upon cAMP signaling pathway stimulation. In osteoblasts, supports transcription activation: phosphorylates RUNX2 that synergizes with SPEN/MINT to enhance FGFR2-mediated activation of the osteocalcin FGF-responsive element (OCFRE). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Interacts with UBL1/SUMO-1 (By similarity). Interacts with and stabilizes ligand-bound androgen receptor (AR). Interacts with Nkx1-2. Interacts with FAS and DAXX. Probably part of a complex consisting of HIPK3, FAS and FADD. Binds to NR5A1/SF1, SPEN/MINT and RUNX2. Heart, skeletal muscle, spleen, testis and lung. Autophosphorylated, but autophosphorylation is not required for catalytic activity. May be sumoylated. Belongs to the protein kinase superfamily. CMGC Ser/Thr protein kinase family. HIPK subfamily.