Stress-activated kinase involved in tolerance to glucose starvation. Induces cell-cell detachment by increasing F-actin conversion to G-actin. Expression is induced by CD95 or TNF-alpha, via NF-kappa-B. Protects cells from CD95-mediated apoptosis and is required for the increased motility and invasiveness of CD95-activated tumor cells. Phosphorylates LATS1 and LATS2. Plays a key role in neural tube closure during embryonic development through LATS2 phosphorylation and regulation of the nuclear localization of YAP1 a critical downstream regulatory target in the Hippo signaling pathway (PubMed:32845958). 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 on Thr-208. Phosphorylated at Thr-208 by STK11/LKB1 in complex with STE20-related adapter-alpha (STRADA) pseudo kinase and CAB39 (PubMed:14976552). Autophosphorylation is also possible at Thr-208 (PubMed:32845958). The disease is caused by variants affecting the gene represented in this entry. Belongs to the protein kinase superfamily. CAMK Ser/Thr protein kinase family. SNF1 subfamily.