Selective peptide inhibitor of glycogen synthase kinase-3 (GSK-3). Produces antidepressive behavior in mice when administered in vivo. Shows no inhibition of PKC, PKB or cdc2 protein kinase. Exhibits insulin mimetic activity. Activates glycogen synthase activity 2.5-fold in HEK293 cells. Myristoylated version of L803 (Cat. No. 2235).