Fig. 6. MEK2-dependent JNK activation. (A) Immunoblots of RD cells transfected with the constitutively active form of HA-tagged MEK2 (CA-MEK2) or with the empty vector (CMV) using antibodies that recognize phospho-active ERKs and hemagglutinin (HA). (B) A luciferase assay for detection of activated JNKs (see Materials and Methods); luciferase activity (units/plates) was assayed in total lysates from RD cells co-transfected with a constitutively active form of MEK2 (CA-MEK2) or with empty vector (CMV) and both with activator plasmid GAL4-Jun and reporter plasmid GAL4-luc. The data shown are representative of two independent experiments.