sentence: The two most evolutionarily conserved candidate sites on NS3 are serine 137 ( S137 ) , which was predicted to be phosphorylated by MAPK , GSK3 , CDK1 , or , and the residue threonine 189 ( T189 ) , which was predicted to be phosphorylated by Kinase AKT , PKB ( AKT ) , or CAMK2G .