Positive test controls include: Jurkat. The target is usually found in the following locations: Nucleus. Immunogen sequence: DDKGDKKNQQ QQQGNNHTNG TGHPGNQDSS HTQGPPLKKV RVVPPTTTSG GLIMTSDYQR SNPHAAYPNP GPSTSQPQSS MGYSATSQQP PQYSHQTHRY. CDK8 phosphorylate