Stress-activated component of a protein kinase signal transduction cascade. Regulates the JNK and p38 pathways (PubMed:11042189). Part of a signaling cascade that begins with the activation of the adrenergic receptor ADRA1B and leads to the activation of MAPK14 (By similarity). Pro-apoptotic. Role in regulation of S and G2 cell cycle checkpoint by direct phosphorylation of CHEK2 (By similarity). Involved in limb development (PubMed:26755636). ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Activated by phosphorylation by PKN1 and autophosphorylation on Thr-161 and Ser-165. Homodimer (PubMed:11042189). Interacts with PKN1 and ZNF33A. Component of a signaling complex containing at least AKAP13, PKN1, MAPK14, MAP3K20 and MAP2K3. Within this complex, AKAP13 interacts directly with PKN1, which in turn recruits MAPK14, MAP2K3 and MAP3K20. Appears to shuttle between nucleus and cytoplasm. Mainly expressed in heart and developing limbs. Knockout results in fully penetrant lethality at 9.5 dpc due to severe cardiac edema and growth retardation. Embryos show polydactyly of the feet. Belongs to the protein kinase superfamily. STE Ser/Thr protein kinase family. MAP kinase kinase kinase subfamily.